Update FTS code

17 files changed, 4228 insertions, 478 deletions

diff --git a/src/libtracker-fts/Makefile.am b/src/libtracker-fts/Makefile.am
index 1780f0623..6e4b7f0ba 100644
--- a/src/libtracker-fts/Makefile.am
+++ b/src/libtracker-fts/Makefile.am
@@ -23,6 +23,8 @@ fts4_sources =                                         \
 	fts3_tokenizer1.c                              \
 	fts3_tokenizer.c                               \
 	fts3_tokenizer.h                               \
+	fts3_unicode.c                                 \
+	fts3_unicode2.c                                \
 	fts3_write.c
 
 libtracker_fts_la_SOURCES =                            \
diff --git a/src/libtracker-fts/fts3.c b/src/libtracker-fts/fts3.c
index f29970dd2..3dc62ba8d 100644
--- a/src/libtracker-fts/fts3.c
+++ b/src/libtracker-fts/fts3.c
@@ -70,7 +70,7 @@
 ** A doclist is stored like this:
 **
 ** array {
-**   varint docid;
+**   varint docid;          (delta from previous doclist)
 **   array {                (position list for column 0)
 **     varint position;     (2 more than the delta from previous position)
 **   }
@@ -101,8 +101,8 @@
 ** at D signals the start of a new column; the 1 at E indicates that the
 ** new column is column number 1.  There are two positions at 12 and 45
 ** (14-2 and 35-2+12).  The 0 at H indicate the end-of-document.  The
-** 234 at I is the next docid.  It has one position 72 (72-2) and then
-** terminates with the 0 at K.
+** 234 at I is the delta to next docid (357).  It has one position 70
+** (72-2) and then terminates with the 0 at K.
 **
 ** A "position-list" is the list of positions for multiple columns for
 ** a single docid.  A "column-list" is the set of positions for a single
@@ -286,10 +286,6 @@
 ** will eventually overtake the earlier data and knock it out.  The
 ** query logic likewise merges doclists so that newer data knocks out
 ** older data.
-**
-** TODO(shess) Provide a VACUUM type operation to clear out all
-** deletions and duplications.  This would basically be a forced merge
-** into a single segment.
 */
 
 #include "fts3Int.h"
@@ -308,8 +304,8 @@
 
 #include "fts3.h"
 #ifndef SQLITE_CORE 
- # include "sqlite3ext.h"
- SQLITE_EXTENSION_INIT1
+# include "sqlite3ext.h"
+  SQLITE_EXTENSION_INIT1
 #endif
 
 static int fts3EvalNext(Fts3Cursor *pCsr);
@@ -438,7 +434,7 @@ static void fts3GetReverseVarint(
   sqlite3_int64 *pVal
 ){
   sqlite3_int64 iVal;
-  char *p = *pp;
+  char *p;
 
   /* Pointer p now points at the first byte past the varint we are 
   ** interested in. So, unless the doclist is corrupt, the 0x80 bit is
@@ -468,6 +464,8 @@ static int fts3DisconnectMethod(sqlite3_vtab *pVtab){
   sqlite3_free(p->zSegmentsTbl);
   sqlite3_free(p->zReadExprlist);
   sqlite3_free(p->zWriteExprlist);
+  sqlite3_free(p->zContentTbl);
+  sqlite3_free(p->zLanguageid);
 
   /* Invoke the tokenizer destructor to free the tokenizer. */
   p->pTokenizer->pModule->xDestroy(p->pTokenizer);
@@ -507,16 +505,19 @@ static void fts3DbExec(
 ** The xDestroy() virtual table method.
 */
 static int fts3DestroyMethod(sqlite3_vtab *pVtab){
-  int rc = SQLITE_OK;              /* Return code */
   Fts3Table *p = (Fts3Table *)pVtab;
-  sqlite3 *db = p->db;
+  int rc = SQLITE_OK;              /* Return code */
+  const char *zDb = p->zDb;        /* Name of database (e.g. "main", "temp") */
+  sqlite3 *db = p->db;             /* Database handle */
 
   /* Drop the shadow tables */
-  fts3DbExec(&rc, db, "DROP TABLE IF EXISTS %Q.'%q_content'", p->zDb, p->zName);
-  fts3DbExec(&rc, db, "DROP TABLE IF EXISTS %Q.'%q_segments'", p->zDb,p->zName);
-  fts3DbExec(&rc, db, "DROP TABLE IF EXISTS %Q.'%q_segdir'", p->zDb, p->zName);
-  fts3DbExec(&rc, db, "DROP TABLE IF EXISTS %Q.'%q_docsize'", p->zDb, p->zName);
-  fts3DbExec(&rc, db, "DROP TABLE IF EXISTS %Q.'%q_stat'", p->zDb, p->zName);
+  if( p->zContentTbl==0 ){
+    fts3DbExec(&rc, db, "DROP TABLE IF EXISTS %Q.'%q_content'", zDb, p->zName);
+  }
+  fts3DbExec(&rc, db, "DROP TABLE IF EXISTS %Q.'%q_segments'", zDb,p->zName);
+  fts3DbExec(&rc, db, "DROP TABLE IF EXISTS %Q.'%q_segdir'", zDb, p->zName);
+  fts3DbExec(&rc, db, "DROP TABLE IF EXISTS %Q.'%q_docsize'", zDb, p->zName);
+  fts3DbExec(&rc, db, "DROP TABLE IF EXISTS %Q.'%q_stat'", zDb, p->zName);
 
   /* If everything has worked, invoke fts3DisconnectMethod() to free the
   ** memory associated with the Fts3Table structure and return SQLITE_OK.
@@ -541,7 +542,9 @@ static void fts3DeclareVtab(int *pRc, Fts3Table *p){
     int rc;                       /* Return code */
     char *zSql;                   /* SQL statement passed to declare_vtab() */
     char *zCols;                  /* List of user defined columns */
+    const char *zLanguageid;
 
+    zLanguageid = (p->zLanguageid ? p->zLanguageid : "__langid");
     sqlite3_vtab_config(p->db, SQLITE_VTAB_CONSTRAINT_SUPPORT, 1);
 
     /* Create a list of user columns for the virtual table */
@@ -552,7 +555,8 @@ static void fts3DeclareVtab(int *pRc, Fts3Table *p){
 
     /* Create the whole "CREATE TABLE" statement to pass to SQLite */
     zSql = sqlite3_mprintf(
-        "CREATE TABLE x(%s %Q HIDDEN, docid HIDDEN)", zCols, p->zName
+        "CREATE TABLE x(%s %Q HIDDEN, docid HIDDEN, %Q HIDDEN)", 
+        zCols, p->zName, zLanguageid
     );
     if( !zCols || !zSql ){
       rc = SQLITE_NOMEM;
@@ -567,6 +571,18 @@ static void fts3DeclareVtab(int *pRc, Fts3Table *p){
 }
 
 /*
+** Create the %_stat table if it does not already exist.
+*/
+void sqlite3Fts3CreateStatTable(int *pRc, Fts3Table *p){
+  fts3DbExec(pRc, p->db, 
+      "CREATE TABLE IF NOT EXISTS %Q.'%q_stat'"
+          "(id INTEGER PRIMARY KEY, value BLOB);",
+      p->zDb, p->zName
+  );
+  if( (*pRc)==SQLITE_OK ) p->bHasStat = 1;
+}
+
+/*
 ** Create the backing store tables (%_content, %_segments and %_segdir)
 ** required by the FTS3 table passed as the only argument. This is done
 ** as part of the vtab xCreate() method.
@@ -578,23 +594,31 @@ static void fts3DeclareVtab(int *pRc, Fts3Table *p){
 static int fts3CreateTables(Fts3Table *p){
   int rc = SQLITE_OK;             /* Return code */
   int i;                          /* Iterator variable */
-  char *zContentCols;             /* Columns of %_content table */
   sqlite3 *db = p->db;            /* The database connection */
 
-  /* Create a list of user columns for the content table */
-  zContentCols = sqlite3_mprintf("docid INTEGER PRIMARY KEY");
-  for(i=0; zContentCols && i<p->nColumn; i++){
-    char *z = p->azColumn[i];
-    zContentCols = sqlite3_mprintf("%z, 'c%d%q'", zContentCols, i, z);
+  if( p->zContentTbl==0 ){
+    const char *zLanguageid = p->zLanguageid;
+    char *zContentCols;           /* Columns of %_content table */
+
+    /* Create a list of user columns for the content table */
+    zContentCols = sqlite3_mprintf("docid INTEGER PRIMARY KEY");
+    for(i=0; zContentCols && i<p->nColumn; i++){
+      char *z = p->azColumn[i];
+      zContentCols = sqlite3_mprintf("%z, 'c%d%q'", zContentCols, i, z);
+    }
+    if( zLanguageid && zContentCols ){
+      zContentCols = sqlite3_mprintf("%z, langid", zContentCols, zLanguageid);
+    }
+    if( zContentCols==0 ) rc = SQLITE_NOMEM;
+  
+    /* Create the content table */
+    fts3DbExec(&rc, db, 
+       "CREATE TABLE %Q.'%q_content'(%s)",
+       p->zDb, p->zName, zContentCols
+    );
+    sqlite3_free(zContentCols);
   }
-  if( zContentCols==0 ) rc = SQLITE_NOMEM;
 
-  /* Create the content table */
-  fts3DbExec(&rc, db, 
-     "CREATE TABLE %Q.'%q_content'(%s)",
-     p->zDb, p->zName, zContentCols
-  );
-  sqlite3_free(zContentCols);
   /* Create other tables */
   fts3DbExec(&rc, db, 
       "CREATE TABLE %Q.'%q_segments'(blockid INTEGER PRIMARY KEY, block BLOB);",
@@ -618,11 +642,9 @@ static int fts3CreateTables(Fts3Table *p){
         p->zDb, p->zName
     );
   }
+  assert( p->bHasStat==p->bFts4 );
   if( p->bHasStat ){
-    fts3DbExec(&rc, db, 
-        "CREATE TABLE %Q.'%q_stat'(id INTEGER PRIMARY KEY, value BLOB);",
-        p->zDb, p->zName
-    );
+    sqlite3Fts3CreateStatTable(&rc, p);
   }
   return rc;
 }
@@ -704,6 +726,7 @@ static void fts3Appendf(
     char *z;
     va_start(ap, zFormat);
     z = sqlite3_vmprintf(zFormat, ap);
+    va_end(ap);
     if( z && *pz ){
       char *z2 = sqlite3_mprintf("%s%s", *pz, z);
       sqlite3_free(z);
@@ -728,7 +751,7 @@ static void fts3Appendf(
 static char *fts3QuoteId(char const *zInput){
   int nRet;
   char *zRet;
-  nRet = 2 + strlen(zInput)*2 + 1;
+  nRet = 2 + (int)strlen(zInput)*2 + 1;
   zRet = sqlite3_malloc(nRet);
   if( zRet ){
     int i;
@@ -745,8 +768,8 @@ static char *fts3QuoteId(char const *zInput){
 }
 
 /*
-** Return a list of comma separated SQL expressions that could be used
-** in a SELECT statement such as the following:
+** Return a list of comma separated SQL expressions and a FROM clause that 
+** could be used in a SELECT statement such as the following:
 **
 **     SELECT <list of expressions> FROM %_content AS x ...
 **
@@ -757,7 +780,7 @@ static char *fts3QuoteId(char const *zInput){
 ** table has the three user-defined columns "a", "b", and "c", the following
 ** string is returned:
 **
-**     "docid, unzip(x.'a'), unzip(x.'b'), unzip(x.'c')"
+**     "docid, unzip(x.'a'), unzip(x.'b'), unzip(x.'c') FROM %_content AS x"
 **
 ** The pointer returned points to a buffer allocated by sqlite3_malloc(). It
 ** is the responsibility of the caller to eventually free it.
@@ -773,16 +796,34 @@ static char *fts3ReadExprList(Fts3Table *p, const char *zFunc, int *pRc){
   char *zFunction;
   int i;
 
-  if( !zFunc ){
-    zFunction = "";
+  if( p->zContentTbl==0 ){
+    if( !zFunc ){
+      zFunction = "";
+    }else{
+      zFree = zFunction = fts3QuoteId(zFunc);
+    }
+    fts3Appendf(pRc, &zRet, "docid");
+    for(i=0; i<p->nColumn; i++){
+      fts3Appendf(pRc, &zRet, ",%s(x.'c%d%q')", zFunction, i, p->azColumn[i]);
+    }
+    if( p->zLanguageid ){
+      fts3Appendf(pRc, &zRet, ", x.%Q", "langid");
+    }
+    sqlite3_free(zFree);
   }else{
-    zFree = zFunction = fts3QuoteId(zFunc);
-  }
-  fts3Appendf(pRc, &zRet, "docid");
-  for(i=0; i<p->nColumn; i++){
-    fts3Appendf(pRc, &zRet, ",%s(x.'c%d%q')", zFunction, i, p->azColumn[i]);
+    fts3Appendf(pRc, &zRet, "rowid");
+    for(i=0; i<p->nColumn; i++){
+      fts3Appendf(pRc, &zRet, ", x.'%q'", p->azColumn[i]);
+    }
+    if( p->zLanguageid ){
+      fts3Appendf(pRc, &zRet, ", x.%Q", p->zLanguageid);
+    }
   }
-  sqlite3_free(zFree);
+  fts3Appendf(pRc, &zRet, " FROM '%q'.'%q%s' AS x", 
+      p->zDb,
+      (p->zContentTbl ? p->zContentTbl : p->zName),
+      (p->zContentTbl ? "" : "_content")
+  );
   return zRet;
 }
 
@@ -821,6 +862,9 @@ static char *fts3WriteExprList(Fts3Table *p, const char *zFunc, int *pRc){
   for(i=0; i<p->nColumn; i++){
     fts3Appendf(pRc, &zRet, ",%s(?)", zFunction);
   }
+  if( p->zLanguageid ){
+    fts3Appendf(pRc, &zRet, ", ?");
+  }
   sqlite3_free(zFree);
   return zRet;
 }
@@ -839,7 +883,7 @@ static char *fts3WriteExprList(Fts3Table *p, const char *zFunc, int *pRc){
 ** This function is used when parsing the "prefix=" FTS4 parameter.
 */
 static int fts3GobbleInt(const char **pp, int *pnOut){
-  const char *p = *pp;            /* Iterator pointer */
+  const char *p;                  /* Iterator pointer */
   int nInt = 0;                   /* Output value */
 
   for(p=*pp; p[0]>='0' && p[0]<='9'; p++){
@@ -907,6 +951,91 @@ static int fts3PrefixParameter(
 }
 
 /*
+** This function is called when initializing an FTS4 table that uses the
+** content=xxx option. It determines the number of and names of the columns
+** of the new FTS4 table.
+**
+** The third argument passed to this function is the value passed to the
+** config=xxx option (i.e. "xxx"). This function queries the database for
+** a table of that name. If found, the output variables are populated
+** as follows:
+**
+**   *pnCol:   Set to the number of columns table xxx has,
+**
+**   *pnStr:   Set to the total amount of space required to store a copy
+**             of each columns name, including the nul-terminator.
+**
+**   *pazCol:  Set to point to an array of *pnCol strings. Each string is
+**             the name of the corresponding column in table xxx. The array
+**             and its contents are allocated using a single allocation. It
+**             is the responsibility of the caller to free this allocation
+**             by eventually passing the *pazCol value to sqlite3_free().
+**
+** If the table cannot be found, an error code is returned and the output
+** variables are undefined. Or, if an OOM is encountered, SQLITE_NOMEM is
+** returned (and the output variables are undefined).
+*/
+static int fts3ContentColumns(
+  sqlite3 *db,                    /* Database handle */
+  const char *zDb,                /* Name of db (i.e. "main", "temp" etc.) */
+  const char *zTbl,               /* Name of content table */
+  const char ***pazCol,           /* OUT: Malloc'd array of column names */
+  int *pnCol,                     /* OUT: Size of array *pazCol */
+  int *pnStr                      /* OUT: Bytes of string content */
+){
+  int rc = SQLITE_OK;             /* Return code */
+  char *zSql;                     /* "SELECT *" statement on zTbl */  
+  sqlite3_stmt *pStmt = 0;        /* Compiled version of zSql */
+
+  zSql = sqlite3_mprintf("SELECT * FROM %Q.%Q", zDb, zTbl);
+  if( !zSql ){
+    rc = SQLITE_NOMEM;
+  }else{
+    rc = sqlite3_prepare(db, zSql, -1, &pStmt, 0);
+  }
+  sqlite3_free(zSql);
+
+  if( rc==SQLITE_OK ){
+    const char **azCol;           /* Output array */
+    int nStr = 0;                 /* Size of all column names (incl. 0x00) */
+    int nCol;                     /* Number of table columns */
+    int i;                        /* Used to iterate through columns */
+
+    /* Loop through the returned columns. Set nStr to the number of bytes of
+    ** space required to store a copy of each column name, including the
+    ** nul-terminator byte.  */
+    nCol = sqlite3_column_count(pStmt);
+    for(i=0; i<nCol; i++){
+      const char *zCol = sqlite3_column_name(pStmt, i);
+      nStr += (int)strlen(zCol) + 1;
+    }
+
+    /* Allocate and populate the array to return. */
+    azCol = (const char **)sqlite3_malloc(sizeof(char *) * nCol + nStr);
+    if( azCol==0 ){
+      rc = SQLITE_NOMEM;
+    }else{
+      char *p = (char *)&azCol[nCol];
+      for(i=0; i<nCol; i++){
+        const char *zCol = sqlite3_column_name(pStmt, i);
+        int n = (int)strlen(zCol)+1;
+        memcpy(p, zCol, n);
+        azCol[i] = p;
+        p += n;
+      }
+    }
+    sqlite3_finalize(pStmt);
+
+    /* Set the output variables. */
+    *pnCol = nCol;
+    *pnStr = nStr;
+    *pazCol = azCol;
+  }
+
+  return rc;
+}
+
+/*
 ** This function is the implementation of both the xConnect and xCreate
 ** methods of the FTS3 virtual table.
 **
@@ -950,6 +1079,8 @@ static int fts3InitVtab(
   char *zPrefix = 0;              /* Prefix parameter value (or NULL) */
   char *zCompress = 0;            /* compress=? parameter (or NULL) */
   char *zUncompress = 0;          /* uncompress=? parameter (or NULL) */
+  char *zContent = 0;             /* content=? parameter (or NULL) */
+  char *zLanguageid = 0;          /* languageid=? parameter (or NULL) */
 
   assert( strlen(argv[0])==4 );
   assert( (sqlite3_strnicmp(argv[0], "fts4", 4)==0 && isFts4)
@@ -993,13 +1124,14 @@ static int fts3InitVtab(
       struct Fts4Option {
         const char *zOpt;
         int nOpt;
-        char **pzVar;
       } aFts4Opt[] = {
-        { "matchinfo",   9, 0 },            /* 0 -> MATCHINFO */
-        { "prefix",      6, 0 },            /* 1 -> PREFIX */
-        { "compress",    8, 0 },            /* 2 -> COMPRESS */
-        { "uncompress", 10, 0 },            /* 3 -> UNCOMPRESS */
-        { "order",       5, 0 }             /* 4 -> ORDER */
+        { "matchinfo",   9 },     /* 0 -> MATCHINFO */
+        { "prefix",      6 },     /* 1 -> PREFIX */
+        { "compress",    8 },     /* 2 -> COMPRESS */
+        { "uncompress", 10 },     /* 3 -> UNCOMPRESS */
+        { "order",       5 },     /* 4 -> ORDER */
+        { "content",     7 },     /* 5 -> CONTENT */
+        { "languageid", 10 }      /* 6 -> LANGUAGEID */
       };
 
       int iOpt;
@@ -1045,13 +1177,26 @@ static int fts3InitVtab(
 
             case 4:               /* ORDER */
               if( (strlen(zVal)!=3 || sqlite3_strnicmp(zVal, "asc", 3)) 
-               && (strlen(zVal)!=4 || sqlite3_strnicmp(zVal, "desc", 3)) 
+               && (strlen(zVal)!=4 || sqlite3_strnicmp(zVal, "desc", 4)) 
               ){
                 *pzErr = sqlite3_mprintf("unrecognized order: %s", zVal);
                 rc = SQLITE_ERROR;
               }
               bDescIdx = (zVal[0]=='d' || zVal[0]=='D');
               break;
+
+            case 5:              /* CONTENT */
+              sqlite3_free(zContent);
+              zContent = zVal;
+              zVal = 0;
+              break;
+
+            case 6:              /* LANGUAGEID */
+              assert( iOpt==6 );
+              sqlite3_free(zLanguageid);
+              zLanguageid = zVal;
+              zVal = 0;
+              break;
           }
         }
         sqlite3_free(zVal);
@@ -1064,6 +1209,39 @@ static int fts3InitVtab(
       aCol[nCol++] = z;
     }
   }
+
+  /* If a content=xxx option was specified, the following:
+  **
+  **   1. Ignore any compress= and uncompress= options.
+  **
+  **   2. If no column names were specified as part of the CREATE VIRTUAL
+  **      TABLE statement, use all columns from the content table.
+  */
+  if( rc==SQLITE_OK && zContent ){
+    sqlite3_free(zCompress); 
+    sqlite3_free(zUncompress); 
+    zCompress = 0;
+    zUncompress = 0;
+    if( nCol==0 ){
+      sqlite3_free((void*)aCol); 
+      aCol = 0;
+      rc = fts3ContentColumns(db, argv[1], zContent, &aCol, &nCol, &nString);
+
+      /* If a languageid= option was specified, remove the language id
+      ** column from the aCol[] array. */ 
+      if( rc==SQLITE_OK && zLanguageid ){
+        int j;
+        for(j=0; j<nCol; j++){
+          if( sqlite3_stricmp(zLanguageid, aCol[j])==0 ){
+            int k;
+            for(k=j; k<nCol; k++) aCol[k] = aCol[k+1];
+            nCol--;
+            break;
+          }
+        }
+      }
+    }
+  }
   if( rc!=SQLITE_OK ) goto fts3_init_out;
 
   if( nCol==0 ){
@@ -1107,7 +1285,13 @@ static int fts3InitVtab(
   p->nMaxPendingData = FTS3_MAX_PENDING_DATA;
   p->bHasDocsize = (isFts4 && bNoDocsize==0);
   p->bHasStat = isFts4;
+  p->bFts4 = isFts4;
   p->bDescIdx = bDescIdx;
+  p->bAutoincrmerge = 0xff;   /* 0xff means setting unknown */
+  p->zContentTbl = zContent;
+  p->zLanguageid = zLanguageid;
+  zContent = 0;
+  zLanguageid = 0;
   TESTONLY( p->inTransaction = -1 );
   TESTONLY( p->mxSavepoint = -1 );
 
@@ -1156,6 +1340,16 @@ static int fts3InitVtab(
     rc = fts3CreateTables(p);
   }
 
+  /* Check to see if a legacy fts3 table has been "upgraded" by the
+  ** addition of a %_stat table so that it can use incremental merge.
+  */
+  if( !isFts4 && !isCreate ){
+    int rc2 = SQLITE_OK;
+    fts3DbExec(&rc2, db, "SELECT 1 FROM %Q.'%q_stat' WHERE id=2",
+               p->zDb, p->zName);
+    if( rc2==SQLITE_OK ) p->bHasStat = 1;
+  }
+
   /* Figure out the page-size for the database. This is required in order to
   ** estimate the cost of loading large doclists from the database.  */
   fts3DatabasePageSize(&rc, p);
@@ -1169,6 +1363,8 @@ fts3_init_out:
   sqlite3_free(aIndex);
   sqlite3_free(zCompress);
   sqlite3_free(zUncompress);
+  sqlite3_free(zContent);
+  sqlite3_free(zLanguageid);
   sqlite3_free((void *)aCol);
   if( rc!=SQLITE_OK ){
     if( p ){
@@ -1220,6 +1416,7 @@ static int fts3BestIndexMethod(sqlite3_vtab *pVTab, sqlite3_index_info *pInfo){
   Fts3Table *p = (Fts3Table *)pVTab;
   int i;                          /* Iterator variable */
   int iCons = -1;                 /* Index of constraint to use */
+  int iLangidCons = -1;           /* Index of langid=x constraint, if present */
 
   /* By default use a full table scan. This is an expensive option,
   ** so search through the constraints to see if a more efficient 
@@ -1232,7 +1429,8 @@ static int fts3BestIndexMethod(sqlite3_vtab *pVTab, sqlite3_index_info *pInfo){
     if( pCons->usable==0 ) continue;
 
     /* A direct lookup on the rowid or docid column. Assign a cost of 1.0. */
-    if( pCons->op==SQLITE_INDEX_CONSTRAINT_EQ 
+    if( iCons<0 
+     && pCons->op==SQLITE_INDEX_CONSTRAINT_EQ 
      && (pCons->iColumn<0 || pCons->iColumn==p->nColumn+1 )
     ){
       pInfo->idxNum = FTS3_DOCID_SEARCH;
@@ -1255,7 +1453,13 @@ static int fts3BestIndexMethod(sqlite3_vtab *pVTab, sqlite3_index_info *pInfo){
       pInfo->idxNum = FTS3_FULLTEXT_SEARCH + pCons->iColumn;
       pInfo->estimatedCost = 2.0;
       iCons = i;
-      break;
+    }
+
+    /* Equality constraint on the langid column */
+    if( pCons->op==SQLITE_INDEX_CONSTRAINT_EQ 
+     && pCons->iColumn==p->nColumn + 2
+    ){
+      iLangidCons = i;
     }
   }
 
@@ -1263,6 +1467,9 @@ static int fts3BestIndexMethod(sqlite3_vtab *pVTab, sqlite3_index_info *pInfo){
     pInfo->aConstraintUsage[iCons].argvIndex = 1;
     pInfo->aConstraintUsage[iCons].omit = 1;
   } 
+  if( iLangidCons>=0 ){
+    pInfo->aConstraintUsage[iLangidCons].argvIndex = 2;
+  } 
 
   /* Regardless of the strategy selected, FTS can deliver rows in rowid (or
   ** docid) order. Both ascending and descending are possible. 
@@ -1321,34 +1528,63 @@ static int fts3CloseMethod(sqlite3_vtab_cursor *pCursor){
 }
 
 /*
+** If pCsr->pStmt has not been prepared (i.e. if pCsr->pStmt==0), then
+** compose and prepare an SQL statement of the form:
+**
+**    "SELECT <columns> FROM %_content WHERE rowid = ?"
+**
+** (or the equivalent for a content=xxx table) and set pCsr->pStmt to
+** it. If an error occurs, return an SQLite error code.
+**
+** Otherwise, set *ppStmt to point to pCsr->pStmt and return SQLITE_OK.
+*/
+static int fts3CursorSeekStmt(Fts3Cursor *pCsr, sqlite3_stmt **ppStmt){
+  int rc = SQLITE_OK;
+  if( pCsr->pStmt==0 ){
+    Fts3Table *p = (Fts3Table *)pCsr->base.pVtab;
+    char *zSql;
+    zSql = sqlite3_mprintf("SELECT %s WHERE rowid = ?", p->zReadExprlist);
+    if( !zSql ) return SQLITE_NOMEM;
+    rc = sqlite3_prepare_v2(p->db, zSql, -1, &pCsr->pStmt, 0);
+    sqlite3_free(zSql);
+  }
+  *ppStmt = pCsr->pStmt;
+  return rc;
+}
+
+/*
 ** Position the pCsr->pStmt statement so that it is on the row
 ** of the %_content table that contains the last match.  Return
 ** SQLITE_OK on success.  
 */
 static int fts3CursorSeek(sqlite3_context *pContext, Fts3Cursor *pCsr){
+  int rc = SQLITE_OK;
   if( pCsr->isRequireSeek ){
-    sqlite3_bind_int64(pCsr->pStmt, 1, pCsr->iPrevId);
-    pCsr->isRequireSeek = 0;
-    if( SQLITE_ROW==sqlite3_step(pCsr->pStmt) ){
-      return SQLITE_OK;
-    }else{
-      int rc = sqlite3_reset(pCsr->pStmt);
-      if( rc==SQLITE_OK ){
-        /* If no row was found and no error has occured, then the %_content
-        ** table is missing a row that is present in the full-text index.
-        ** The data structures are corrupt.
-        */
-        rc = SQLITE_CORRUPT_VTAB;
-      }
-      pCsr->isEof = 1;
-      if( pContext ){
-        sqlite3_result_error_code(pContext, rc);
+    sqlite3_stmt *pStmt = 0;
+
+    rc = fts3CursorSeekStmt(pCsr, &pStmt);
+    if( rc==SQLITE_OK ){
+      sqlite3_bind_int64(pCsr->pStmt, 1, pCsr->iPrevId);
+      pCsr->isRequireSeek = 0;
+      if( SQLITE_ROW==sqlite3_step(pCsr->pStmt) ){
+        return SQLITE_OK;
+      }else{
+        rc = sqlite3_reset(pCsr->pStmt);
+        if( rc==SQLITE_OK && ((Fts3Table *)pCsr->base.pVtab)->zContentTbl==0 ){
+          /* If no row was found and no error has occured, then the %_content
+          ** table is missing a row that is present in the full-text index.
+          ** The data structures are corrupt.  */
+          rc = FTS_CORRUPT_VTAB;
+          pCsr->isEof = 1;
+        }
       }
-      return rc;
     }
-  }else{
-    return SQLITE_OK;
   }
+
+  if( rc!=SQLITE_OK && pContext ){
+    sqlite3_result_error_code(pContext, rc);
+  }
+  return rc;
 }
 
 /*
@@ -1398,7 +1634,7 @@ static int fts3ScanInteriorNode(
   zCsr += sqlite3Fts3GetVarint(zCsr, &iChild);
   zCsr += sqlite3Fts3GetVarint(zCsr, &iChild);
   if( zCsr>zEnd ){
-    return SQLITE_CORRUPT_VTAB;
+    return FTS_CORRUPT_VTAB;
   }
   
   while( zCsr<zEnd && (piFirst || piLast) ){
@@ -1416,7 +1652,7 @@ static int fts3ScanInteriorNode(
     zCsr += sqlite3Fts3GetVarint32(zCsr, &nSuffix);
     
     if( nPrefix<0 || nSuffix<0 || &zCsr[nSuffix]>zEnd ){
-      rc = SQLITE_CORRUPT_VTAB;
+      rc = FTS_CORRUPT_VTAB;
       goto finish_scan;
     }
     if( nPrefix+nSuffix>nAlloc ){
@@ -1429,6 +1665,7 @@ static int fts3ScanInteriorNode(
       }
       zBuffer = zNew;
     }
+    assert( zBuffer );
     memcpy(&zBuffer[nPrefix], zCsr, nSuffix);
     nBuffer = nPrefix + nSuffix;
     zCsr += nSuffix;
@@ -1787,7 +2024,7 @@ static int fts3PoslistPhraseMerge(
   char **pp1,                     /* IN/OUT: Left input list */
   char **pp2                      /* IN/OUT: Right input list */
 ){
-  char *p = (pp ? *pp : 0);
+  char *p = *pp;
   char *p1 = *pp1;
   char *p2 = *pp2;
   int iCol1 = 0;
@@ -1796,7 +2033,7 @@ static int fts3PoslistPhraseMerge(
   /* Never set both isSaveLeft and isExact for the same invocation. */
   assert( isSaveLeft==0 || isExact==0 );
 
-  assert( *p1!=0 && *p2!=0 );
+  assert( p!=0 && *p1!=0 && *p2!=0 );
   if( *p1==POS_COLUMN ){ 
     p1++;
     p1 += sqlite3Fts3GetVarint32(p1, &iCol1);
@@ -1813,7 +2050,7 @@ static int fts3PoslistPhraseMerge(
       sqlite3_int64 iPos1 = 0;
       sqlite3_int64 iPos2 = 0;
 
-      if( pp && iCol1 ){
+      if( iCol1 ){
         *p++ = POS_COLUMN;
         p += sqlite3Fts3PutVarint(p, iCol1);
       }
@@ -1828,16 +2065,10 @@ static int fts3PoslistPhraseMerge(
          || (isExact==0 && iPos2>iPos1 && iPos2<=iPos1+nToken) 
         ){
           sqlite3_int64 iSave;
-          if( !pp ){
-            fts3PoslistCopy(0, &p2);
-            fts3PoslistCopy(0, &p1);
-            *pp1 = p1;
-            *pp2 = p2;
-            return 1;
-          }
           iSave = isSaveLeft ? iPos1 : iPos2;
           fts3PutDeltaVarint(&p, &iPrev, iSave+2); iPrev -= 2;
           pSave = 0;
+          assert( p );
         }
         if( (!isSaveLeft && iPos2<=(iPos1+nToken)) || iPos2<=iPos1 ){
           if( (*p2&0xFE)==0 ) break;
@@ -1886,7 +2117,7 @@ static int fts3PoslistPhraseMerge(
   fts3PoslistCopy(0, &p1);
   *pp1 = p1;
   *pp2 = p2;
-  if( !pp || *pp==p ){
+  if( *pp==p ){
     return 0;
   }
   *p++ = 0x00;
@@ -2122,7 +2353,7 @@ static int fts3DoclistOrMerge(
   }
 
   *paOut = aOut;
-  *pnOut = (p-aOut);
+  *pnOut = (int)(p-aOut);
   assert( *pnOut<=n1+n2+FTS3_VARINT_MAX-1 );
   return SQLITE_OK;
 }
@@ -2186,7 +2417,57 @@ static void fts3DoclistPhraseMerge(
     }
   }
 
-  *pnRight = p - aOut;
+  *pnRight = (int)(p - aOut);
+}
+
+/*
+** Argument pList points to a position list nList bytes in size. This
+** function checks to see if the position list contains any entries for
+** a token in position 0 (of any column). If so, it writes argument iDelta
+** to the output buffer pOut, followed by a position list consisting only
+** of the entries from pList at position 0, and terminated by an 0x00 byte.
+** The value returned is the number of bytes written to pOut (if any).
+*/
+int sqlite3Fts3FirstFilter(
+  sqlite3_int64 iDelta,           /* Varint that may be written to pOut */
+  char *pList,                    /* Position list (no 0x00 term) */
+  int nList,                      /* Size of pList in bytes */
+  char *pOut                      /* Write output here */
+){
+  int nOut = 0;
+  int bWritten = 0;               /* True once iDelta has been written */
+  char *p = pList;
+  char *pEnd = &pList[nList];
+
+  if( *p!=0x01 ){
+    if( *p==0x02 ){
+      nOut += sqlite3Fts3PutVarint(&pOut[nOut], iDelta);
+      pOut[nOut++] = 0x02;
+      bWritten = 1;
+    }
+    fts3ColumnlistCopy(0, &p);
+  }
+
+  while( p<pEnd && *p==0x01 ){
+    sqlite3_int64 iCol;
+    p++;
+    p += sqlite3Fts3GetVarint(p, &iCol);
+    if( *p==0x02 ){
+      if( bWritten==0 ){
+        nOut += sqlite3Fts3PutVarint(&pOut[nOut], iDelta);
+        bWritten = 1;
+      }
+      pOut[nOut++] = 0x01;
+      nOut += sqlite3Fts3PutVarint(&pOut[nOut], iCol);
+      pOut[nOut++] = 0x02;
+    }
+    fts3ColumnlistCopy(0, &p);
+  }
+  if( bWritten ){
+    pOut[nOut++] = 0x00;
+  }
+
+  return nOut;
 }
 
 
@@ -2338,6 +2619,7 @@ static int fts3SegReaderCursorAppend(
 */
 static int fts3SegReaderCursor(
   Fts3Table *p,                   /* FTS3 table handle */
+  int iLangid,                    /* Language id */
   int iIndex,                     /* Index to search (from 0 to p->nIndex-1) */
   int iLevel,                     /* Level of segments to scan */
   const char *zTerm,              /* Term to query for */
@@ -2366,7 +2648,7 @@ static int fts3SegReaderCursor(
 
   if( iLevel!=FTS3_SEGCURSOR_PENDING ){
     if( rc==SQLITE_OK ){
-      rc = sqlite3Fts3AllSegdirs(p, iIndex, iLevel, &pStmt);
+      rc = sqlite3Fts3AllSegdirs(p, iLangid, iIndex, iLevel, &pStmt);
     }
 
     while( rc==SQLITE_OK && SQLITE_ROW==(rc = sqlite3_step(pStmt)) ){
@@ -2389,7 +2671,9 @@ static int fts3SegReaderCursor(
       }
  
       rc = sqlite3Fts3SegReaderNew(pCsr->nSegment+1, 
-          iStartBlock, iLeavesEndBlock, iEndBlock, zRoot, nRoot, &pSeg
+          (isPrefix==0 && isScan==0),
+          iStartBlock, iLeavesEndBlock, 
+          iEndBlock, zRoot, nRoot, &pSeg
       );
       if( rc!=SQLITE_OK ) goto finished;
       rc = fts3SegReaderCursorAppend(pCsr, pSeg);
@@ -2409,6 +2693,7 @@ static int fts3SegReaderCursor(
 */
 int sqlite3Fts3SegReaderCursor(
   Fts3Table *p,                   /* FTS3 table handle */
+  int iLangid,                    /* Language-id to search */
   int iIndex,                     /* Index to search (from 0 to p->nIndex-1) */
   int iLevel,                     /* Level of segments to scan */
   const char *zTerm,              /* Term to query for */
@@ -2426,14 +2711,9 @@ int sqlite3Fts3SegReaderCursor(
   assert( FTS3_SEGCURSOR_ALL<0 && FTS3_SEGCURSOR_PENDING<0 );
   assert( isPrefix==0 || isScan==0 );
 
-  /* "isScan" is only set to true by the ft4aux module, an ordinary
-  ** full-text tables. */
-  assert( isScan==0 || p->aIndex==0 );
-
   memset(pCsr, 0, sizeof(Fts3MultiSegReader));
-
   return fts3SegReaderCursor(
-      p, iIndex, iLevel, zTerm, nTerm, isPrefix, isScan, pCsr
+      p, iLangid, iIndex, iLevel, zTerm, nTerm, isPrefix, isScan, pCsr
   );
 }
 
@@ -2445,11 +2725,14 @@ int sqlite3Fts3SegReaderCursor(
 */
 static int fts3SegReaderCursorAddZero(
   Fts3Table *p,                   /* FTS virtual table handle */
+  int iLangid,
   const char *zTerm,              /* Term to scan doclist of */
   int nTerm,                      /* Number of bytes in zTerm */
   Fts3MultiSegReader *pCsr        /* Fts3MultiSegReader to modify */
 ){
-  return fts3SegReaderCursor(p, 0, FTS3_SEGCURSOR_ALL, zTerm, nTerm, 0, 0,pCsr);
+  return fts3SegReaderCursor(p, 
+      iLangid, 0, FTS3_SEGCURSOR_ALL, zTerm, nTerm, 0, 0,pCsr
+  );
 }
 
 /*
@@ -2485,8 +2768,9 @@ static int fts3TermSegReaderCursor(
       for(i=1; bFound==0 && i<p->nIndex; i++){
         if( p->aIndex[i].nPrefix==nTerm ){
           bFound = 1;
-          rc = sqlite3Fts3SegReaderCursor(
-              p, i, FTS3_SEGCURSOR_ALL, zTerm, nTerm, 0, 0, pSegcsr);
+          rc = sqlite3Fts3SegReaderCursor(p, pCsr->iLangid, 
+              i, FTS3_SEGCURSOR_ALL, zTerm, nTerm, 0, 0, pSegcsr
+          );
           pSegcsr->bLookup = 1;
         }
       }
@@ -2494,19 +2778,21 @@ static int fts3TermSegReaderCursor(
       for(i=1; bFound==0 && i<p->nIndex; i++){
         if( p->aIndex[i].nPrefix==nTerm+1 ){
           bFound = 1;
-          rc = sqlite3Fts3SegReaderCursor(
-              p, i, FTS3_SEGCURSOR_ALL, zTerm, nTerm, 1, 0, pSegcsr
+          rc = sqlite3Fts3SegReaderCursor(p, pCsr->iLangid, 
+              i, FTS3_SEGCURSOR_ALL, zTerm, nTerm, 1, 0, pSegcsr
           );
           if( rc==SQLITE_OK ){
-            rc = fts3SegReaderCursorAddZero(p, zTerm, nTerm, pSegcsr);
+            rc = fts3SegReaderCursorAddZero(
+                p, pCsr->iLangid, zTerm, nTerm, pSegcsr
+            );
           }
         }
       }
     }
 
     if( bFound==0 ){
-      rc = sqlite3Fts3SegReaderCursor(
-          p, 0, FTS3_SEGCURSOR_ALL, zTerm, nTerm, isPrefix, 0, pSegcsr
+      rc = sqlite3Fts3SegReaderCursor(p, pCsr->iLangid, 
+          0, FTS3_SEGCURSOR_ALL, zTerm, nTerm, isPrefix, 0, pSegcsr
       );
       pSegcsr->bLookup = !isPrefix;
     }
@@ -2545,6 +2831,7 @@ static int fts3TermSelect(
 
   filter.flags = FTS3_SEGMENT_IGNORE_EMPTY | FTS3_SEGMENT_REQUIRE_POS
         | (pTok->isPrefix ? FTS3_SEGMENT_PREFIX : 0)
+        | (pTok->bFirst ? FTS3_SEGMENT_FIRST : 0)
         | (iColumn<p->nColumn ? FTS3_SEGMENT_COLUMN_FILTER : 0);
   filter.iCol = iColumn;
   filter.zTerm = pTok->z;
@@ -2660,7 +2947,7 @@ static int fts3FilterMethod(
   UNUSED_PARAMETER(nVal);
 
   assert( idxNum>=0 && idxNum<=(FTS3_FULLTEXT_SEARCH+p->nColumn) );
-  assert( nVal==0 || nVal==1 );
+  assert( nVal==0 || nVal==1 || nVal==2 );
   assert( (nVal==0)==(idxNum==FTS3_FULLSCAN_SEARCH) );
   assert( p->pSegments==0 );
 
@@ -2685,8 +2972,11 @@ static int fts3FilterMethod(
       return SQLITE_NOMEM;
     }
 
-    rc = sqlite3Fts3ExprParse(p->pTokenizer, p->azColumn, p->nColumn, 
-        iCol, zQuery, -1, &pCsr->pExpr
+    pCsr->iLangid = 0;
+    if( nVal==2 ) pCsr->iLangid = sqlite3_value_int(apVal[1]);
+
+    rc = sqlite3Fts3ExprParse(p->pTokenizer, pCsr->iLangid,
+        p->azColumn, p->bFts4, p->nColumn, iCol, zQuery, -1, &pCsr->pExpr
     );
     if( rc!=SQLITE_OK ){
       if( rc==SQLITE_ERROR ){
@@ -2713,23 +3003,24 @@ static int fts3FilterMethod(
   ** row by docid.
   */
   if( idxNum==FTS3_FULLSCAN_SEARCH ){
-    const char *zSort = (pCsr->bDesc ? "DESC" : "ASC");
-    const char *zTmpl = "SELECT %s FROM %Q.'%q_content' AS x ORDER BY docid %s";
-    zSql = sqlite3_mprintf(zTmpl, p->zReadExprlist, p->zDb, p->zName, zSort);
-  }else{
-    const char *zTmpl = "SELECT %s FROM %Q.'%q_content' AS x WHERE docid = ?";
-    zSql = sqlite3_mprintf(zTmpl, p->zReadExprlist, p->zDb, p->zName);
+    zSql = sqlite3_mprintf(
+        "SELECT %s ORDER BY rowid %s",
+        p->zReadExprlist, (pCsr->bDesc ? "DESC" : "ASC")
+    );
+    if( zSql ){
+      rc = sqlite3_prepare_v2(p->db, zSql, -1, &pCsr->pStmt, 0);
+      sqlite3_free(zSql);
+    }else{
+      rc = SQLITE_NOMEM;
+    }
+  }else if( idxNum==FTS3_DOCID_SEARCH ){
+    rc = fts3CursorSeekStmt(pCsr, &pCsr->pStmt);
+    if( rc==SQLITE_OK ){
+      rc = sqlite3_bind_value(pCsr->pStmt, 1, apVal[0]);
+    }
   }
-  if( !zSql ) return SQLITE_NOMEM;
-  rc = sqlite3_prepare_v2(p->db, zSql, -1, &pCsr->pStmt, 0);
-  sqlite3_free(zSql);
   if( rc!=SQLITE_OK ) return rc;
 
-  if( idxNum==FTS3_DOCID_SEARCH ){
-    rc = sqlite3_bind_value(pCsr->pStmt, 1, apVal[0]);
-    if( rc!=SQLITE_OK ) return rc;
-  }
-
   return fts3NextMethod(pCursor);
 }
 
@@ -2756,10 +3047,17 @@ static int fts3RowidMethod(sqlite3_vtab_cursor *pCursor, sqlite_int64 *pRowid){
 /* 
 ** This is the xColumn method, called by SQLite to request a value from
 ** the row that the supplied cursor currently points to.
+**
+** If:
+**
+**   (iCol <  p->nColumn)   -> The value of the iCol'th user column.
+**   (iCol == p->nColumn)   -> Magic column with the same name as the table.
+**   (iCol == p->nColumn+1) -> Docid column
+**   (iCol == p->nColumn+2) -> Langid column
 */
 static int fts3ColumnMethod(
   sqlite3_vtab_cursor *pCursor,   /* Cursor to retrieve value from */
-  sqlite3_context *pContext,      /* Context for sqlite3_result_xxx() calls */
+  sqlite3_context *pCtx,          /* Context for sqlite3_result_xxx() calls */
   int iCol                        /* Index of column to read value from */
 ){
   int rc = SQLITE_OK;             /* Return Code */
@@ -2767,22 +3065,34 @@ static int fts3ColumnMethod(
   Fts3Table *p = (Fts3Table *)pCursor->pVtab;
 
   /* The column value supplied by SQLite must be in range. */
-  assert( iCol>=0 && iCol<=p->nColumn+1 );
+  assert( iCol>=0 && iCol<=p->nColumn+2 );
 
   if( iCol==p->nColumn+1 ){
     /* This call is a request for the "docid" column. Since "docid" is an 
     ** alias for "rowid", use the xRowid() method to obtain the value.
     */
-    sqlite3_result_int64(pContext, pCsr->iPrevId);
+    sqlite3_result_int64(pCtx, pCsr->iPrevId);
   }else if( iCol==p->nColumn ){
     /* The extra column whose name is the same as the table.
-    ** Return a blob which is a pointer to the cursor.
-    */
-    sqlite3_result_blob(pContext, &pCsr, sizeof(pCsr), SQLITE_TRANSIENT);
+    ** Return a blob which is a pointer to the cursor.  */
+    sqlite3_result_blob(pCtx, &pCsr, sizeof(pCsr), SQLITE_TRANSIENT);
+  }else if( iCol==p->nColumn+2 && pCsr->pExpr ){
+    sqlite3_result_int64(pCtx, pCsr->iLangid);
   }else{
+    /* The requested column is either a user column (one that contains 
+    ** indexed data), or the language-id column.  */
     rc = fts3CursorSeek(0, pCsr);
+
     if( rc==SQLITE_OK ){
-      sqlite3_result_value(pContext, sqlite3_column_value(pCsr->pStmt, iCol+1));
+      if( iCol==p->nColumn+2 ){
+        int iLangid = 0;
+        if( p->zLanguageid ){
+          iLangid = sqlite3_column_int(pCsr->pStmt, p->nColumn+1);
+        }
+        sqlite3_result_int(pCtx, iLangid);
+      }else if( sqlite3_data_count(pCsr->pStmt)>(iCol+1) ){
+        sqlite3_result_value(pCtx, sqlite3_column_value(pCsr->pStmt, iCol+1));
+      }
     }
   }
 
@@ -2809,8 +3119,42 @@ static int fts3UpdateMethod(
 ** hash-table to the database.
 */
 static int fts3SyncMethod(sqlite3_vtab *pVtab){
-  int rc = sqlite3Fts3PendingTermsFlush((Fts3Table *)pVtab);
-  sqlite3Fts3SegmentsClose((Fts3Table *)pVtab);
+
+  /* Following an incremental-merge operation, assuming that the input
+  ** segments are not completely consumed (the usual case), they are updated
+  ** in place to remove the entries that have already been merged. This
+  ** involves updating the leaf block that contains the smallest unmerged
+  ** entry and each block (if any) between the leaf and the root node. So
+  ** if the height of the input segment b-trees is N, and input segments
+  ** are merged eight at a time, updating the input segments at the end
+  ** of an incremental-merge requires writing (8*(1+N)) blocks. N is usually
+  ** small - often between 0 and 2. So the overhead of the incremental
+  ** merge is somewhere between 8 and 24 blocks. To avoid this overhead
+  ** dwarfing the actual productive work accomplished, the incremental merge
+  ** is only attempted if it will write at least 64 leaf blocks. Hence
+  ** nMinMerge.
+  **
+  ** Of course, updating the input segments also involves deleting a bunch
+  ** of blocks from the segments table. But this is not considered overhead
+  ** as it would also be required by a crisis-merge that used the same input 
+  ** segments.
+  */
+  const u32 nMinMerge = 64;       /* Minimum amount of incr-merge work to do */
+
+  Fts3Table *p = (Fts3Table*)pVtab;
+  int rc = sqlite3Fts3PendingTermsFlush(p);
+
+  if( rc==SQLITE_OK && p->bAutoincrmerge==1 && p->nLeafAdd>(nMinMerge/16) ){
+    int mxLevel = 0;              /* Maximum relative level value in db */
+    int A;                        /* Incr-merge parameter A */
+
+    rc = sqlite3Fts3MaxLevel(p, &mxLevel);
+    assert( rc==SQLITE_OK || mxLevel==0 );
+    A = p->nLeafAdd * mxLevel;
+    A += (A/2);
+    if( A>(int)nMinMerge ) rc = sqlite3Fts3Incrmerge(p, A, 8);
+  }
+  sqlite3Fts3SegmentsClose(p);
   return rc;
 }
 
@@ -2818,13 +3162,14 @@ static int fts3SyncMethod(sqlite3_vtab *pVtab){
 ** Implementation of xBegin() method. This is a no-op.
 */
 static int fts3BeginMethod(sqlite3_vtab *pVtab){
-  TESTONLY( Fts3Table *p = (Fts3Table*)pVtab );
+  Fts3Table *p = (Fts3Table*)pVtab;
   UNUSED_PARAMETER(pVtab);
   assert( p->pSegments==0 );
   assert( p->nPendingData==0 );
   assert( p->inTransaction!=1 );
   TESTONLY( p->inTransaction = 1 );
   TESTONLY( p->mxSavepoint = -1; );
+  p->nLeafAdd = 0;
   return SQLITE_OK;
 }
 
@@ -2865,7 +3210,7 @@ static int fts3RollbackMethod(sqlite3_vtab *pVtab){
 */
 static void fts3ReversePoslist(char *pStart, char **ppPoslist){
   char *p = &(*ppPoslist)[-2];
-  char c;
+  char c = 0;
 
   while( p>pStart && (c=*p--)==0 );
   while( p>pStart && (*p & 0x80) | c ){ 
@@ -3074,15 +3419,22 @@ static int fts3RenameMethod(
   sqlite3 *db = p->db;            /* Database connection */
   int rc;                         /* Return Code */
 
+  /* As it happens, the pending terms table is always empty here. This is
+  ** because an "ALTER TABLE RENAME TABLE" statement inside a transaction 
+  ** always opens a savepoint transaction. And the xSavepoint() method 
+  ** flushes the pending terms table. But leave the (no-op) call to
+  ** PendingTermsFlush() in in case that changes.
+  */
+  assert( p->nPendingData==0 );
   rc = sqlite3Fts3PendingTermsFlush(p);
-  if( rc!=SQLITE_OK ){
-    return rc;
+
+  if( p->zContentTbl==0 ){
+    fts3DbExec(&rc, db,
+      "ALTER TABLE %Q.'%q_content'  RENAME TO '%q_content';",
+      p->zDb, p->zName, zName
+    );
   }
 
-  fts3DbExec(&rc, db,
-    "ALTER TABLE %Q.'%q_content'  RENAME TO '%q_content';",
-    p->zDb, p->zName, zName
-  );
   if( p->bHasDocsize ){
     fts3DbExec(&rc, db,
       "ALTER TABLE %Q.'%q_docsize'  RENAME TO '%q_docsize';",
@@ -3112,11 +3464,15 @@ static int fts3RenameMethod(
 ** Flush the contents of the pending-terms table to disk.
 */
 static int fts3SavepointMethod(sqlite3_vtab *pVtab, int iSavepoint){
+  int rc = SQLITE_OK;
   UNUSED_PARAMETER(iSavepoint);
   assert( ((Fts3Table *)pVtab)->inTransaction );
   assert( ((Fts3Table *)pVtab)->mxSavepoint < iSavepoint );
   TESTONLY( ((Fts3Table *)pVtab)->mxSavepoint = iSavepoint );
-  return fts3SyncMethod(pVtab);
+  if( ((Fts3Table *)pVtab)->bIgnoreSavepoint==0 ){
+    rc = fts3SyncMethod(pVtab);
+  }
+  return rc;
 }
 
 /*
@@ -3198,6 +3554,9 @@ static void hashDestroy(void *p){
 */
 void sqlite3Fts3SimpleTokenizerModule(sqlite3_tokenizer_module const**ppModule);
 void sqlite3Fts3PorterTokenizerModule(sqlite3_tokenizer_module const**ppModule);
+#ifdef SQLITE_ENABLE_FTS4_UNICODE61
+void sqlite3Fts3UnicodeTokenizer(sqlite3_tokenizer_module const**ppModule);
+#endif
 #ifdef SQLITE_ENABLE_ICU
 void sqlite3Fts3IcuTokenizerModule(sqlite3_tokenizer_module const**ppModule);
 #endif
@@ -3213,12 +3572,19 @@ int sqlite3Fts3Init(sqlite3 *db){
   Fts3Hash *pHash = 0;
   const sqlite3_tokenizer_module *pSimple = 0;
   const sqlite3_tokenizer_module *pPorter = 0;
+#ifdef SQLITE_ENABLE_FTS4_UNICODE61
+  const sqlite3_tokenizer_module *pUnicode = 0;
+#endif
 
 #ifdef SQLITE_ENABLE_ICU
   const sqlite3_tokenizer_module *pIcu = 0;
   sqlite3Fts3IcuTokenizerModule(&pIcu);
 #endif
 
+#ifdef SQLITE_ENABLE_FTS4_UNICODE61
+  sqlite3Fts3UnicodeTokenizer(&pUnicode);
+#endif
+
 #ifdef SQLITE_TEST
   rc = sqlite3Fts3InitTerm(db);
   if( rc!=SQLITE_OK ) return rc;
@@ -3242,6 +3608,10 @@ int sqlite3Fts3Init(sqlite3 *db){
   if( rc==SQLITE_OK ){
     if( sqlite3Fts3HashInsert(pHash, "simple", 7, (void *)pSimple)
      || sqlite3Fts3HashInsert(pHash, "porter", 7, (void *)pPorter) 
+
+#ifdef SQLITE_ENABLE_FTS4_UNICODE61
+     || sqlite3Fts3HashInsert(pHash, "unicode61", 10, (void *)pUnicode) 
+#endif
 #ifdef SQLITE_ENABLE_ICU
      || (pIcu && sqlite3Fts3HashInsert(pHash, "icu", 4, (void *)pIcu))
 #endif
@@ -3441,21 +3811,20 @@ static int fts3EvalPhraseLoad(
 */
 static int fts3EvalDeferredPhrase(Fts3Cursor *pCsr, Fts3Phrase *pPhrase){
   int iToken;                     /* Used to iterate through phrase tokens */
-  int rc = SQLITE_OK;             /* Return code */
   char *aPoslist = 0;             /* Position list for deferred tokens */
   int nPoslist = 0;               /* Number of bytes in aPoslist */
   int iPrev = -1;                 /* Token number of previous deferred token */
 
   assert( pPhrase->doclist.bFreeList==0 );
 
-  for(iToken=0; rc==SQLITE_OK && iToken<pPhrase->nToken; iToken++){
+  for(iToken=0; iToken<pPhrase->nToken; iToken++){
     Fts3PhraseToken *pToken = &pPhrase->aToken[iToken];
     Fts3DeferredToken *pDeferred = pToken->pDeferred;
 
     if( pDeferred ){
       char *pList;
       int nList;
-      rc = sqlite3Fts3DeferredTokenList(pDeferred, &pList, &nList);
+      int rc = sqlite3Fts3DeferredTokenList(pDeferred, &pList, &nList);
       if( rc!=SQLITE_OK ) return rc;
 
       if( pList==0 ){
@@ -3477,7 +3846,7 @@ static int fts3EvalDeferredPhrase(Fts3Cursor *pCsr, Fts3Phrase *pPhrase){
         fts3PoslistPhraseMerge(&aOut, iToken-iPrev, 0, 1, &p1, &p2);
         sqlite3_free(aPoslist);
         aPoslist = pList;
-        nPoslist = aOut - aPoslist;
+        nPoslist = (int)(aOut - aPoslist);
         if( nPoslist==0 ){
           sqlite3_free(aPoslist);
           pPhrase->doclist.pList = 0;
@@ -3521,7 +3890,7 @@ static int fts3EvalDeferredPhrase(Fts3Cursor *pCsr, Fts3Phrase *pPhrase){
       pPhrase->doclist.pList = aOut;
       if( fts3PoslistPhraseMerge(&aOut, nDistance, 0, 1, &p1, &p2) ){
         pPhrase->doclist.bFreeList = 1;
-        pPhrase->doclist.nList = (aOut - pPhrase->doclist.pList);
+        pPhrase->doclist.nList = (int)(aOut - pPhrase->doclist.pList);
       }else{
         sqlite3_free(aOut);
         pPhrase->doclist.pList = 0;
@@ -3556,6 +3925,7 @@ static int fts3EvalPhraseStart(Fts3Cursor *pCsr, int bOptOk, Fts3Phrase *p){
    && p->nToken==1 
    && pFirst->pSegcsr 
    && pFirst->pSegcsr->bLookup 
+   && pFirst->bFirst==0
   ){
     /* Use the incremental approach. */
     int iCol = (p->iColumn >= pTab->nColumn ? -1 : p->iColumn);
@@ -3589,7 +3959,7 @@ void sqlite3Fts3DoclistPrev(
   int nDoclist,                   /* Length of aDoclist in bytes */
   char **ppIter,                  /* IN/OUT: Iterator pointer */
   sqlite3_int64 *piDocid,         /* IN/OUT: Docid pointer */
-  int *pnList,                    /* IN/OUT: List length pointer */
+  int *pnList,                    /* OUT: List length pointer */
   u8 *pbEof                       /* OUT: End-of-file flag */
 ){
   char *p = *ppIter;
@@ -3616,7 +3986,7 @@ void sqlite3Fts3DoclistPrev(
       iMul = (bDescIdx ? -1 : 1);
     }
 
-    *pnList = pEnd - pNext;
+    *pnList = (int)(pEnd - pNext);
     *ppIter = pNext;
     *piDocid = iDocid;
   }else{
@@ -3630,13 +4000,48 @@ void sqlite3Fts3DoclistPrev(
     }else{
       char *pSave = p;
       fts3ReversePoslist(aDoclist, &p);
-      *pnList = (pSave - p);
+      *pnList = (int)(pSave - p);
     }
     *ppIter = p;
   }
 }
 
 /*
+** Iterate forwards through a doclist.
+*/
+void sqlite3Fts3DoclistNext(
+  int bDescIdx,                   /* True if the doclist is desc */
+  char *aDoclist,                 /* Pointer to entire doclist */
+  int nDoclist,                   /* Length of aDoclist in bytes */
+  char **ppIter,                  /* IN/OUT: Iterator pointer */
+  sqlite3_int64 *piDocid,         /* IN/OUT: Docid pointer */
+  u8 *pbEof                       /* OUT: End-of-file flag */
+){
+  char *p = *ppIter;
+
+  assert( nDoclist>0 );
+  assert( *pbEof==0 );
+  assert( p || *piDocid==0 );
+  assert( !p || (p>=aDoclist && p<=&aDoclist[nDoclist]) );
+
+  if( p==0 ){
+    p = aDoclist;
+    p += sqlite3Fts3GetVarint(p, piDocid);
+  }else{
+    fts3PoslistCopy(0, &p);
+    if( p>=&aDoclist[nDoclist] ){
+      *pbEof = 1;
+    }else{
+      sqlite3_int64 iVar;
+      p += sqlite3Fts3GetVarint(p, &iVar);
+      *piDocid += ((bDescIdx ? -1 : 1) * iVar);
+    }
+  }
+
+  *ppIter = p;
+}
+
+/*
 ** Attempt to move the phrase iterator to point to the next matching docid. 
 ** If an error occurs, return an SQLite error code. Otherwise, return 
 ** SQLITE_OK.
@@ -3690,7 +4095,7 @@ static int fts3EvalPhraseNext(
       }
       pDL->pList = pIter;
       fts3PoslistCopy(0, &pIter);
-      pDL->nList = (pIter - pDL->pList);
+      pDL->nList = (int)(pIter - pDL->pList);
 
       /* pIter now points just past the 0x00 that terminates the position-
       ** list for document pDL->iDocid. However, if this position-list was
@@ -3785,7 +4190,7 @@ static void fts3EvalTokenCosts(
   Fts3Expr ***ppOr,               /* Write new OR root to *(*ppOr)++ */
   int *pRc                        /* IN/OUT: Error code */
 ){
-  if( *pRc==SQLITE_OK && pExpr ){
+  if( *pRc==SQLITE_OK ){
     if( pExpr->eType==FTSQUERY_PHRASE ){
       Fts3Phrase *pPhrase = pExpr->pPhrase;
       int i;
@@ -3799,6 +4204,11 @@ static void fts3EvalTokenCosts(
         *pRc = sqlite3Fts3MsrOvfl(pCsr, pTC->pToken->pSegcsr, &pTC->nOvfl);
       }
     }else if( pExpr->eType!=FTSQUERY_NOT ){
+      assert( pExpr->eType==FTSQUERY_OR
+           || pExpr->eType==FTSQUERY_AND
+           || pExpr->eType==FTSQUERY_NEAR
+      );
+      assert( pExpr->pLeft && pExpr->pRight );
       if( pExpr->eType==FTSQUERY_OR ){
         pRoot = pExpr->pLeft;
         **ppOr = pRoot;
@@ -3859,7 +4269,7 @@ static int fts3EvalAverageDocsize(Fts3Cursor *pCsr, int *pnPage){
     }
     if( nDoc==0 || nByte==0 ){
       sqlite3_reset(pStmt);
-      return SQLITE_CORRUPT_VTAB;
+      return FTS_CORRUPT_VTAB;
     }
 
     pCsr->nDoc = nDoc;
@@ -3903,6 +4313,15 @@ static int fts3EvalSelectDeferred(
   int nMinEst = 0;                /* The minimum count for any phrase so far. */
   int nLoad4 = 1;                 /* (Phrases that will be loaded)^4. */
 
+  /* Tokens are never deferred for FTS tables created using the content=xxx
+  ** option. The reason being that it is not guaranteed that the content
+  ** table actually contains the same data as the index. To prevent this from
+  ** causing any problems, the deferred token optimization is completely
+  ** disabled for content=xxx tables. */
+  if( pTab->zContentTbl ){
+    return SQLITE_OK;
+  }
+
   /* Count the tokens in this AND/NEAR cluster. If none of the doclists
   ** associated with the tokens spill onto overflow pages, or if there is
   ** only 1 token, exit early. No tokens to defer in this case. */
@@ -3965,7 +4384,11 @@ static int fts3EvalSelectDeferred(
       fts3SegReaderCursorFree(pToken->pSegcsr);
       pToken->pSegcsr = 0;
     }else{
-      nLoad4 = nLoad4*4;
+      /* Set nLoad4 to the value of (4^nOther) for the next iteration of the
+      ** for-loop. Except, limit the value to 2^24 to prevent it from 
+      ** overflowing the 32-bit integer it is stored in. */
+      if( ii<12 ) nLoad4 = nLoad4*4;
+
       if( ii==0 || pTC->pPhrase->nToken>1 ){
         /* Either this is the cheapest token in the entire query, or it is
         ** part of a multi-token phrase. Either way, the entire doclist will
@@ -4013,7 +4436,8 @@ static int fts3EvalStart(Fts3Cursor *pCsr){
   fts3EvalAllocateReaders(pCsr, pCsr->pExpr, &nToken, &nOr, &rc);
 
   /* Determine which, if any, tokens in the expression should be deferred. */
-  if( rc==SQLITE_OK && nToken>1 && pTab->bHasStat ){
+#ifndef SQLITE_DISABLE_FTS4_DEFERRED
+  if( rc==SQLITE_OK && nToken>1 && pTab->bFts4 ){
     Fts3TokenAndCost *aTC;
     Fts3Expr **apOr;
     aTC = (Fts3TokenAndCost *)sqlite3_malloc(
@@ -4030,8 +4454,8 @@ static int fts3EvalStart(Fts3Cursor *pCsr){
       Fts3Expr **ppOr = apOr;
 
       fts3EvalTokenCosts(pCsr, 0, pCsr->pExpr, &pTC, &ppOr, &rc);
-      nToken = pTC-aTC;
-      nOr = ppOr-apOr;
+      nToken = (int)(pTC-aTC);
+      nOr = (int)(ppOr-apOr);
 
       if( rc==SQLITE_OK ){
         rc = fts3EvalSelectDeferred(pCsr, 0, aTC, nToken);
@@ -4043,6 +4467,7 @@ static int fts3EvalStart(Fts3Cursor *pCsr){
       sqlite3_free(aTC);
     }
   }
+#endif
 
   fts3EvalStartReaders(pCsr, pCsr->pExpr, 1, &rc);
   return rc;
@@ -4103,7 +4528,7 @@ static int fts3EvalNearTrim(
     &pOut, aTmp, nParam1, nParam2, paPoslist, &p2
   );
   if( res ){
-    nNew = (pOut - pPhrase->doclist.pList) - 1;
+    nNew = (int)(pOut - pPhrase->doclist.pList) - 1;
     assert( pPhrase->doclist.pList[nNew]=='\0' );
     assert( nNew<=pPhrase->doclist.nList && nNew>0 );
     memset(&pPhrase->doclist.pList[nNew], 0, pPhrase->doclist.nList - nNew);
@@ -4318,32 +4743,39 @@ static int fts3EvalNearTest(Fts3Expr *pExpr, int *pRc){
       nTmp += p->pRight->pPhrase->doclist.nList;
     }
     nTmp += p->pPhrase->doclist.nList;
-    aTmp = sqlite3_malloc(nTmp*2);
-    if( !aTmp ){
-      *pRc = SQLITE_NOMEM;
+    if( nTmp==0 ){
       res = 0;
     }else{
-      char *aPoslist = p->pPhrase->doclist.pList;
-      int nToken = p->pPhrase->nToken;
+      aTmp = sqlite3_malloc(nTmp*2);
+      if( !aTmp ){
+        *pRc = SQLITE_NOMEM;
+        res = 0;
+      }else{
+        char *aPoslist = p->pPhrase->doclist.pList;
+        int nToken = p->pPhrase->nToken;
 
-      for(p=p->pParent;res && p && p->eType==FTSQUERY_NEAR; p=p->pParent){
-        Fts3Phrase *pPhrase = p->pRight->pPhrase;
-        int nNear = p->nNear;
-        res = fts3EvalNearTrim(nNear, aTmp, &aPoslist, &nToken, pPhrase);
-      }
-  
-      aPoslist = pExpr->pRight->pPhrase->doclist.pList;
-      nToken = pExpr->pRight->pPhrase->nToken;
-      for(p=pExpr->pLeft; p && res; p=p->pLeft){
-        int nNear = p->pParent->nNear;
-        Fts3Phrase *pPhrase = (
-            p->eType==FTSQUERY_NEAR ? p->pRight->pPhrase : p->pPhrase
-        );
-        res = fts3EvalNearTrim(nNear, aTmp, &aPoslist, &nToken, pPhrase);
+        for(p=p->pParent;res && p && p->eType==FTSQUERY_NEAR; p=p->pParent){
+          Fts3Phrase *pPhrase = p->pRight->pPhrase;
+          int nNear = p->nNear;
+          res = fts3EvalNearTrim(nNear, aTmp, &aPoslist, &nToken, pPhrase);
+        }
+
+        aPoslist = pExpr->pRight->pPhrase->doclist.pList;
+        nToken = pExpr->pRight->pPhrase->nToken;
+        for(p=pExpr->pLeft; p && res; p=p->pLeft){
+          int nNear;
+          Fts3Phrase *pPhrase;
+          assert( p->pParent && p->pParent->pLeft==p );
+          nNear = p->pParent->nNear;
+          pPhrase = (
+              p->eType==FTSQUERY_NEAR ? p->pRight->pPhrase : p->pPhrase
+              );
+          res = fts3EvalNearTrim(nNear, aTmp, &aPoslist, &nToken, pPhrase);
+        }
       }
-    }
 
-    sqlite3_free(aTmp);
+      sqlite3_free(aTmp);
+    }
   }
 
   return res;
@@ -4423,6 +4855,7 @@ static int fts3EvalTestExpr(
         break;
 
       default: {
+#ifndef SQLITE_DISABLE_FTS4_DEFERRED
         if( pCsr->pDeferred 
          && (pExpr->iDocid==pCsr->iPrevId || pExpr->bDeferred)
         ){
@@ -4434,7 +4867,9 @@ static int fts3EvalTestExpr(
           *pRc = fts3EvalDeferredPhrase(pCsr, pPhrase);
           bHit = (pPhrase->doclist.pList!=0);
           pExpr->iDocid = pCsr->iPrevId;
-        }else{
+        }else
+#endif
+        {
           bHit = (pExpr->bEof==0 && pExpr->iDocid==pCsr->iPrevId);
         }
         break;
@@ -4770,26 +5205,87 @@ int sqlite3Fts3EvalPhraseStats(
 ** This function works regardless of whether or not the phrase is deferred,
 ** incremental, or neither.
 */
-char *sqlite3Fts3EvalPhrasePoslist(
+int sqlite3Fts3EvalPhrasePoslist(
   Fts3Cursor *pCsr,               /* FTS3 cursor object */
   Fts3Expr *pExpr,                /* Phrase to return doclist for */
-  int iCol                        /* Column to return position list for */
+  int iCol,                       /* Column to return position list for */
+  char **ppOut                    /* OUT: Pointer to position list */
 ){
   Fts3Phrase *pPhrase = pExpr->pPhrase;
   Fts3Table *pTab = (Fts3Table *)pCsr->base.pVtab;
-  char *pIter = pPhrase->doclist.pList;
+  char *pIter;
   int iThis;
+  sqlite3_int64 iDocid;
 
+  /* If this phrase is applies specifically to some column other than 
+  ** column iCol, return a NULL pointer.  */
+  *ppOut = 0;
   assert( iCol>=0 && iCol<pTab->nColumn );
-  if( !pIter 
-   || pExpr->bEof 
-   || pExpr->iDocid!=pCsr->iPrevId
-   || (pPhrase->iColumn<pTab->nColumn && pPhrase->iColumn!=iCol) 
-  ){
-    return 0;
+  if( (pPhrase->iColumn<pTab->nColumn && pPhrase->iColumn!=iCol) ){
+    return SQLITE_OK;
+  }
+
+  iDocid = pExpr->iDocid;
+  pIter = pPhrase->doclist.pList;
+  if( iDocid!=pCsr->iPrevId || pExpr->bEof ){
+    int bDescDoclist = pTab->bDescIdx;      /* For DOCID_CMP macro */
+    int bOr = 0;
+    u8 bEof = 0;
+    Fts3Expr *p;
+
+    /* Check if this phrase descends from an OR expression node. If not, 
+    ** return NULL. Otherwise, the entry that corresponds to docid 
+    ** pCsr->iPrevId may lie earlier in the doclist buffer. */
+    for(p=pExpr->pParent; p; p=p->pParent){
+      if( p->eType==FTSQUERY_OR ) bOr = 1;
+    }
+    if( bOr==0 ) return SQLITE_OK;
+
+    /* This is the descendent of an OR node. In this case we cannot use
+    ** an incremental phrase. Load the entire doclist for the phrase
+    ** into memory in this case.  */
+    if( pPhrase->bIncr ){
+      int rc = SQLITE_OK;
+      int bEofSave = pExpr->bEof;
+      fts3EvalRestart(pCsr, pExpr, &rc);
+      while( rc==SQLITE_OK && !pExpr->bEof ){
+        fts3EvalNextRow(pCsr, pExpr, &rc);
+        if( bEofSave==0 && pExpr->iDocid==iDocid ) break;
+      }
+      pIter = pPhrase->doclist.pList;
+      assert( rc!=SQLITE_OK || pPhrase->bIncr==0 );
+      if( rc!=SQLITE_OK ) return rc;
+    }
+
+    if( pExpr->bEof ){
+      pIter = 0;
+      iDocid = 0;
+    }
+    bEof = (pPhrase->doclist.nAll==0);
+    assert( bDescDoclist==0 || bDescDoclist==1 );
+    assert( pCsr->bDesc==0 || pCsr->bDesc==1 );
+
+    if( pCsr->bDesc==bDescDoclist ){
+      int dummy;
+      while( (pIter==0 || DOCID_CMP(iDocid, pCsr->iPrevId)>0 ) && bEof==0 ){
+        sqlite3Fts3DoclistPrev(
+            bDescDoclist, pPhrase->doclist.aAll, pPhrase->doclist.nAll, 
+            &pIter, &iDocid, &dummy, &bEof
+        );
+      }
+    }else{
+      while( (pIter==0 || DOCID_CMP(iDocid, pCsr->iPrevId)<0 ) && bEof==0 ){
+        sqlite3Fts3DoclistNext(
+            bDescDoclist, pPhrase->doclist.aAll, pPhrase->doclist.nAll, 
+            &pIter, &iDocid, &bEof
+        );
+      }
+    }
+
+    if( bEof || iDocid!=pCsr->iPrevId ) pIter = 0;
   }
+  if( pIter==0 ) return SQLITE_OK;
 
-  assert( pPhrase->doclist.nList>0 );
   if( *pIter==0x01 ){
     pIter++;
     pIter += sqlite3Fts3GetVarint32(pIter, &iThis);
@@ -4803,7 +5299,8 @@ char *sqlite3Fts3EvalPhrasePoslist(
     pIter += sqlite3Fts3GetVarint32(pIter, &iThis);
   }
 
-  return ((iCol==iThis)?pIter:0);
+  *ppOut = ((iCol==iThis)?pIter:0);
+  return SQLITE_OK;
 }
 
 /*
@@ -4826,6 +5323,16 @@ void sqlite3Fts3EvalPhraseCleanup(Fts3Phrase *pPhrase){
   }
 }
 
+
+/*
+** Return SQLITE_CORRUPT_VTAB.
+*/
+#ifdef SQLITE_DEBUG
+int sqlite3Fts3Corrupt(){
+  return SQLITE_CORRUPT_VTAB;
+}
+#endif
+
 #if !SQLITE_CORE
 /*
 ** Initialize API pointer table, if required.
diff --git a/src/libtracker-fts/fts3.h b/src/libtracker-fts/fts3.h
index 4a06f637f..b0346826d 100644
--- a/src/libtracker-fts/fts3.h
+++ b/src/libtracker-fts/fts3.h
@@ -20,9 +20,12 @@ extern "C" {
 #endif  /* __cplusplus */
 
 int sqlite3Fts3Init(sqlite3 *db);
-int fts4_extension_init(sqlite3 *db,
-                        char **pzErrMsg,
-                        void *pApi);
+
+int fts4_extension_init(
+  sqlite3 *db, 
+  char **pzErrMsg,
+  void *pApi
+);
 
 #ifdef __cplusplus
 }  /* extern "C" */
diff --git a/src/libtracker-fts/fts3Int.h b/src/libtracker-fts/fts3Int.h
index ed8043adf..77ca4704e 100644
--- a/src/libtracker-fts/fts3Int.h
+++ b/src/libtracker-fts/fts3Int.h
@@ -67,6 +67,9 @@ extern const sqlite3_api_routines *sqlite3_api;
 #ifndef MIN
 # define MIN(x,y) ((x)<(y)?(x):(y))
 #endif
+#ifndef MAX
+# define MAX(x,y) ((x)>(y)?(x):(y))
+#endif
 
 /*
 ** Maximum length of a varint encoded integer. The varint format is different
@@ -121,7 +124,7 @@ extern const sqlite3_api_routines *sqlite3_api;
 # define NEVER(X)  (0)
 #else
 # define ALWAYS(x) (x)
-# define NEVER(X)  (x)
+# define NEVER(x)  (x)
 #endif
 
 /*
@@ -131,6 +134,7 @@ typedef unsigned char u8;         /* 1-byte (or larger) unsigned integer */
 typedef short int i16;            /* 2-byte (or larger) signed integer */
 typedef unsigned int u32;         /* 4-byte unsigned integer */
 typedef sqlite3_uint64 u64;       /* 8-byte unsigned integer */
+typedef sqlite3_int64 i64;        /* 8-byte signed integer */
 
 /*
 ** Macro used to suppress compiler warnings for unused parameters.
@@ -157,6 +161,13 @@ typedef sqlite3_uint64 u64;       /* 8-byte unsigned integer */
 
 #endif /* SQLITE_AMALGAMATION */
 
+#ifdef SQLITE_DEBUG
+int sqlite3Fts3Corrupt(void);
+# define FTS_CORRUPT_VTAB sqlite3Fts3Corrupt()
+#else
+# define FTS_CORRUPT_VTAB SQLITE_CORRUPT_VTAB
+#endif
+
 typedef struct Fts3Table Fts3Table;
 typedef struct Fts3Cursor Fts3Cursor;
 typedef struct Fts3Expr Fts3Expr;
@@ -184,36 +195,45 @@ struct Fts3Table {
   int nColumn;                    /* number of named columns in virtual table */
   char **azColumn;                /* column names.  malloced */
   sqlite3_tokenizer *pTokenizer;  /* tokenizer for inserts and queries */
+  char *zContentTbl;              /* content=xxx option, or NULL */
+  char *zLanguageid;              /* languageid=xxx option, or NULL */
+  u8 bAutoincrmerge;              /* True if automerge=1 */
+  u32 nLeafAdd;                   /* Number of leaf blocks added this trans */
 
   /* Precompiled statements used by the implementation. Each of these 
   ** statements is run and reset within a single virtual table API call. 
   */
-  sqlite3_stmt *aStmt[27];
+  sqlite3_stmt *aStmt[37];
 
   char *zReadExprlist;
   char *zWriteExprlist;
 
   int nNodeSize;                  /* Soft limit for node size */
+  u8 bFts4;                       /* True for FTS4, false for FTS3 */
   u8 bHasStat;                    /* True if %_stat table exists */
   u8 bHasDocsize;                 /* True if %_docsize table exists */
   u8 bDescIdx;                    /* True if doclists are in reverse order */
+  u8 bIgnoreSavepoint;            /* True to ignore xSavepoint invocations */
   int nPgsz;                      /* Page size for host database */
   char *zSegmentsTbl;             /* Name of %_segments table */
   sqlite3_blob *pSegments;        /* Blob handle open on %_segments table */
 
-  /* TODO: Fix the first paragraph of this comment.
-  **
-  ** The following hash table is used to buffer pending index updates during
-  ** transactions. Variable nPendingData estimates the memory size of the 
-  ** pending data, including hash table overhead, but not malloc overhead. 
-  ** When nPendingData exceeds nMaxPendingData, the buffer is flushed 
-  ** automatically. Variable iPrevDocid is the docid of the most recently
-  ** inserted record.
+  /* 
+  ** The following array of hash tables is used to buffer pending index 
+  ** updates during transactions. All pending updates buffered at any one
+  ** time must share a common language-id (see the FTS4 langid= feature).
+  ** The current language id is stored in variable iPrevLangid.
   **
   ** A single FTS4 table may have multiple full-text indexes. For each index
   ** there is an entry in the aIndex[] array. Index 0 is an index of all the
   ** terms that appear in the document set. Each subsequent index in aIndex[]
   ** is an index of prefixes of a specific length.
+  **
+  ** Variable nPendingData contains an estimate the memory consumed by the 
+  ** pending data structures, including hash table overhead, but not including
+  ** malloc overhead.  When nPendingData exceeds nMaxPendingData, all hash
+  ** tables are flushed to disk. Variable iPrevDocid is the docid of the most 
+  ** recently inserted record.
   */
   int nIndex;                     /* Size of aIndex[] */
   struct Fts3Index {
@@ -223,12 +243,13 @@ struct Fts3Table {
   int nMaxPendingData;            /* Max pending data before flush to disk */
   int nPendingData;               /* Current bytes of pending data */
   sqlite_int64 iPrevDocid;        /* Docid of most recently inserted document */
+  int iPrevLangid;                /* Langid of recently inserted document */
 
-#if defined(SQLITE_DEBUG)
+#if defined(SQLITE_DEBUG) || defined(SQLITE_COVERAGE_TEST)
   /* State variables used for validating that the transaction control
   ** methods of the virtual table are called at appropriate times.  These
-  ** values do not contribution to the FTS computation; they are used for
-  ** verifying the SQLite core.
+  ** values do not contribute to FTS functionality; they are used for
+  ** verifying the operation of the SQLite core.
   */
   int inTransaction;     /* True after xBegin but before xCommit/xRollback */
   int mxSavepoint;       /* Largest valid xSavepoint integer */
@@ -247,6 +268,7 @@ struct Fts3Cursor {
   u8 isRequireSeek;               /* True if must seek pStmt to %_content row */
   sqlite3_stmt *pStmt;            /* Prepared statement in use by the cursor */
   Fts3Expr *pExpr;                /* Parsed MATCH query string */
+  int iLangid;                    /* Language being queried for */
   int nPhrase;                    /* Number of matchable phrases in query */
   Fts3DeferredToken *pDeferred;   /* Deferred search tokens, if any */
   sqlite3_int64 iPrevId;          /* Previous id read from aDoclist */
@@ -309,6 +331,7 @@ struct Fts3PhraseToken {
   char *z;                        /* Text of the token */
   int n;                          /* Number of bytes in buffer z */
   int isPrefix;                   /* True if token ends with a "*" character */
+  int bFirst;                     /* True if token must appear at position 0 */
 
   /* Variables above this point are populated when the expression is
   ** parsed (by code in fts3_expr.c). Below this point the variables are
@@ -392,23 +415,34 @@ int sqlite3Fts3UpdateMethod(sqlite3_vtab*,int,sqlite3_value**,sqlite3_int64*);
 int sqlite3Fts3PendingTermsFlush(Fts3Table *);
 void sqlite3Fts3PendingTermsClear(Fts3Table *);
 int sqlite3Fts3Optimize(Fts3Table *);
-int sqlite3Fts3SegReaderNew(int, sqlite3_int64,
+int sqlite3Fts3SegReaderNew(int, int, sqlite3_int64,
   sqlite3_int64, sqlite3_int64, const char *, int, Fts3SegReader**);
 int sqlite3Fts3SegReaderPending(
   Fts3Table*,int,const char*,int,int,Fts3SegReader**);
 void sqlite3Fts3SegReaderFree(Fts3SegReader *);
-int sqlite3Fts3AllSegdirs(Fts3Table*, int, int, sqlite3_stmt **);
+int sqlite3Fts3AllSegdirs(Fts3Table*, int, int, int, sqlite3_stmt **);
 int sqlite3Fts3ReadLock(Fts3Table *);
 int sqlite3Fts3ReadBlock(Fts3Table*, sqlite3_int64, char **, int*, int*);
 
 int sqlite3Fts3SelectDoctotal(Fts3Table *, sqlite3_stmt **);
 int sqlite3Fts3SelectDocsize(Fts3Table *, sqlite3_int64, sqlite3_stmt **);
 
+#ifndef SQLITE_DISABLE_FTS4_DEFERRED
 void sqlite3Fts3FreeDeferredTokens(Fts3Cursor *);
 int sqlite3Fts3DeferToken(Fts3Cursor *, Fts3PhraseToken *, int);
 int sqlite3Fts3CacheDeferredDoclists(Fts3Cursor *);
 void sqlite3Fts3FreeDeferredDoclists(Fts3Cursor *);
+int sqlite3Fts3DeferredTokenList(Fts3DeferredToken *, char **, int *);
+#else
+# define sqlite3Fts3FreeDeferredTokens(x)
+# define sqlite3Fts3DeferToken(x,y,z) SQLITE_OK
+# define sqlite3Fts3CacheDeferredDoclists(x) SQLITE_OK
+# define sqlite3Fts3FreeDeferredDoclists(x)
+# define sqlite3Fts3DeferredTokenList(x,y,z) SQLITE_OK
+#endif
+
 void sqlite3Fts3SegmentsClose(Fts3Table *);
+int sqlite3Fts3MaxLevel(Fts3Table *, int *);
 
 /* Special values interpreted by sqlite3SegReaderCursor() */
 #define FTS3_SEGCURSOR_PENDING        -1
@@ -418,8 +452,8 @@ int sqlite3Fts3SegReaderStart(Fts3Table*, Fts3MultiSegReader*, Fts3SegFilter*);
 int sqlite3Fts3SegReaderStep(Fts3Table *, Fts3MultiSegReader *);
 void sqlite3Fts3SegReaderFinish(Fts3MultiSegReader *);
 
-int sqlite3Fts3SegReaderCursor(
-    Fts3Table *, int, int, const char *, int, int, int, Fts3MultiSegReader *);
+int sqlite3Fts3SegReaderCursor(Fts3Table *, 
+    int, int, int, const char *, int, int, int, Fts3MultiSegReader *);
 
 /* Flags allowed as part of the 4th argument to SegmentReaderIterate() */
 #define FTS3_SEGMENT_REQUIRE_POS   0x00000001
@@ -427,6 +461,7 @@ int sqlite3Fts3SegReaderCursor(
 #define FTS3_SEGMENT_COLUMN_FILTER 0x00000004
 #define FTS3_SEGMENT_PREFIX        0x00000008
 #define FTS3_SEGMENT_SCAN          0x00000010
+#define FTS3_SEGMENT_FIRST         0x00000020
 
 /* Type passed as 4th argument to SegmentReaderIterate() */
 struct Fts3SegFilter {
@@ -459,6 +494,8 @@ struct Fts3MultiSegReader {
   int nDoclist;                   /* Size of aDoclist[] in bytes */
 };
 
+int sqlite3Fts3Incrmerge(Fts3Table*,int,int);
+
 /* fts3.c */
 int sqlite3Fts3PutVarint(char *, sqlite3_int64);
 int sqlite3Fts3GetVarint(const char *, sqlite_int64 *);
@@ -466,8 +503,9 @@ int sqlite3Fts3GetVarint32(const char *, int *);
 int sqlite3Fts3VarintLen(sqlite3_uint64);
 void sqlite3Fts3Dequote(char *);
 void sqlite3Fts3DoclistPrev(int,char*,int,char**,sqlite3_int64*,int*,u8*);
-
 int sqlite3Fts3EvalPhraseStats(Fts3Cursor *, Fts3Expr *, u32 *);
+int sqlite3Fts3FirstFilter(sqlite3_int64, char *, int, char *);
+void sqlite3Fts3CreateStatTable(int*, Fts3Table*);
 
 /* fts3_tokenizer.c */
 const char *sqlite3Fts3NextToken(const char *, int *);
@@ -485,8 +523,8 @@ void sqlite3Fts3Snippet(sqlite3_context *, Fts3Cursor *, const char *,
 void sqlite3Fts3Matchinfo(sqlite3_context *, Fts3Cursor *, const char *);
 
 /* fts3_expr.c */
-int sqlite3Fts3ExprParse(sqlite3_tokenizer *, 
-  char **, int, int, const char *, int, Fts3Expr **
+int sqlite3Fts3ExprParse(sqlite3_tokenizer *, int,
+  char **, int, int, int, const char *, int, Fts3Expr **
 );
 void sqlite3Fts3ExprFree(Fts3Expr *);
 #ifdef SQLITE_TEST
@@ -494,6 +532,10 @@ int sqlite3Fts3ExprInitTestInterface(sqlite3 *db);
 int sqlite3Fts3InitTerm(sqlite3 *db);
 #endif
 
+int sqlite3Fts3OpenTokenizer(sqlite3_tokenizer *, int, const char *, int,
+  sqlite3_tokenizer_cursor **
+);
+
 /* fts3_aux.c */
 int sqlite3Fts3InitAux(sqlite3 *db);
 
@@ -503,11 +545,16 @@ int sqlite3Fts3MsrIncrStart(
     Fts3Table*, Fts3MultiSegReader*, int, const char*, int);
 int sqlite3Fts3MsrIncrNext(
     Fts3Table *, Fts3MultiSegReader *, sqlite3_int64 *, char **, int *);
-char *sqlite3Fts3EvalPhrasePoslist(Fts3Cursor *, Fts3Expr *, int iCol); 
+int sqlite3Fts3EvalPhrasePoslist(Fts3Cursor *, Fts3Expr *, int iCol, char **); 
 int sqlite3Fts3MsrOvfl(Fts3Cursor *, Fts3MultiSegReader *, int *);
 int sqlite3Fts3MsrIncrRestart(Fts3MultiSegReader *pCsr);
 
-int sqlite3Fts3DeferredTokenList(Fts3DeferredToken *, char **, int *);
+/* fts3_unicode2.c (functions generated by parsing unicode text files) */
+#ifdef SQLITE_ENABLE_FTS4_UNICODE61
+int sqlite3FtsUnicodeFold(int, int);
+int sqlite3FtsUnicodeIsalnum(int);
+int sqlite3FtsUnicodeIsdiacritic(int);
+#endif
 
 #endif /* !SQLITE_CORE || SQLITE_ENABLE_FTS3 */
 #endif /* _FTSINT_H */
diff --git a/src/libtracker-fts/fts3_aux.c b/src/libtracker-fts/fts3_aux.c
index ada85d796..a2bff2e1d 100644
--- a/src/libtracker-fts/fts3_aux.c
+++ b/src/libtracker-fts/fts3_aux.c
@@ -79,9 +79,9 @@ static int fts3auxConnectMethod(
   }
 
   zDb = argv[1]; 
-  nDb = strlen(zDb);
+  nDb = (int)strlen(zDb);
   zFts3 = argv[3];
-  nFts3 = strlen(zFts3);
+  nFts3 = (int)strlen(zFts3);
 
   rc = sqlite3_declare_vtab(db, FTS3_TERMS_SCHEMA);
   if( rc!=SQLITE_OK ) return rc;
@@ -376,7 +376,7 @@ static int fts3auxFilterMethod(
     if( pCsr->zStop==0 ) return SQLITE_NOMEM;
   }
 
-  rc = sqlite3Fts3SegReaderCursor(pFts3, 0, FTS3_SEGCURSOR_ALL,
+  rc = sqlite3Fts3SegReaderCursor(pFts3, 0, 0, FTS3_SEGCURSOR_ALL,
       pCsr->filter.zTerm, pCsr->filter.nTerm, 0, isScan, &pCsr->csr
   );
   if( rc==SQLITE_OK ){
diff --git a/src/libtracker-fts/fts3_expr.c b/src/libtracker-fts/fts3_expr.c
index 7eb2962d4..7612789de 100644
--- a/src/libtracker-fts/fts3_expr.c
+++ b/src/libtracker-fts/fts3_expr.c
@@ -92,7 +92,9 @@ int sqlite3_fts3_enable_parentheses = 0;
 typedef struct ParseContext ParseContext;
 struct ParseContext {
   sqlite3_tokenizer *pTokenizer;      /* Tokenizer module */
+  int iLangid;                        /* Language id used with tokenizer */
   const char **azCol;                 /* Array of column names for fts3 table */
+  int bFts4;                          /* True to allow FTS4-only syntax */
   int nCol;                           /* Number of entries in azCol[] */
   int iDefaultCol;                    /* Default column to query */
   int isNot;                          /* True if getNextNode() sees a unary - */
@@ -126,6 +128,33 @@ static void *fts3MallocZero(int nByte){
   return pRet;
 }
 
+int sqlite3Fts3OpenTokenizer(
+  sqlite3_tokenizer *pTokenizer,
+  int iLangid,
+  const char *z,
+  int n,
+  sqlite3_tokenizer_cursor **ppCsr
+){
+  sqlite3_tokenizer_module const *pModule = pTokenizer->pModule;
+  sqlite3_tokenizer_cursor *pCsr = 0;
+  int rc;
+
+  rc = pModule->xOpen(pTokenizer, z, n, &pCsr);
+  assert( rc==SQLITE_OK || pCsr==0 );
+  if( rc==SQLITE_OK ){
+    pCsr->pTokenizer = pTokenizer;
+    if( pModule->iVersion>=1 ){
+      rc = pModule->xLanguageid(pCsr, iLangid);
+      if( rc!=SQLITE_OK ){
+        pModule->xClose(pCsr);
+        pCsr = 0;
+      }
+    }
+  }
+  *ppCsr = pCsr;
+  return rc;
+}
+
 
 /*
 ** Extract the next token from buffer z (length n) using the tokenizer
@@ -153,15 +182,13 @@ static int getNextToken(
   Fts3Expr *pRet = 0;
   int nConsumed = 0;
 
-  rc = pModule->xOpen(pTokenizer, z, n, &pCursor);
+  rc = sqlite3Fts3OpenTokenizer(pTokenizer, pParse->iLangid, z, n, &pCursor);
   if( rc==SQLITE_OK ){
     const char *zToken;
-    int nToken, iStart, iEnd, iPosition;
+    int nToken = 0, iStart = 0, iEnd = 0, iPosition = 0;
     int nByte;                               /* total space to allocate */
 
-    pCursor->pTokenizer = pTokenizer;
     rc = pModule->xNext(pCursor, &zToken, &nToken, &iStart, &iEnd, &iPosition);
-
     if( rc==SQLITE_OK ){
       nByte = sizeof(Fts3Expr) + sizeof(Fts3Phrase) + nToken;
       pRet = (Fts3Expr *)fts3MallocZero(nByte);
@@ -180,9 +207,21 @@ static int getNextToken(
           pRet->pPhrase->aToken[0].isPrefix = 1;
           iEnd++;
         }
-        if( !sqlite3_fts3_enable_parentheses && iStart>0 && z[iStart-1]=='-' ){
-          pParse->isNot = 1;
+
+        while( 1 ){
+          if( !sqlite3_fts3_enable_parentheses 
+           && iStart>0 && z[iStart-1]=='-' 
+          ){
+            pParse->isNot = 1;
+            iStart--;
+          }else if( pParse->bFts4 && iStart>0 && z[iStart-1]=='^' ){
+            pRet->pPhrase->aToken[0].bFirst = 1;
+            iStart--;
+          }else{
+            break;
+          }
         }
+
       }
       nConsumed = iEnd;
     }
@@ -255,13 +294,13 @@ static int getNextString(
   ** appends buffer zTemp to buffer p, and fills in the Fts3Expr and Fts3Phrase
   ** structures.
   */
-  rc = pModule->xOpen(pTokenizer, zInput, nInput, &pCursor);
+  rc = sqlite3Fts3OpenTokenizer(
+      pTokenizer, pParse->iLangid, zInput, nInput, &pCursor);
   if( rc==SQLITE_OK ){
     int ii;
-    pCursor->pTokenizer = pTokenizer;
     for(ii=0; rc==SQLITE_OK; ii++){
       const char *zByte;
-      int nByte, iBegin, iEnd, iPos;
+      int nByte = 0, iBegin = 0, iEnd = 0, iPos = 0;
       rc = pModule->xNext(pCursor, &zByte, &nByte, &iBegin, &iEnd, &iPos);
       if( rc==SQLITE_OK ){
         Fts3PhraseToken *pToken;
@@ -281,6 +320,7 @@ static int getNextString(
 
         pToken->n = nByte;
         pToken->isPrefix = (iEnd<nInput && zInput[iEnd]=='*');
+        pToken->bFirst = (iBegin>0 && zInput[iBegin-1]=='^');
         nToken = ii+1;
       }
     }
@@ -302,8 +342,12 @@ static int getNextString(
     p->pPhrase->nToken = nToken;
 
     zBuf = (char *)&p->pPhrase->aToken[nToken];
-    memcpy(zBuf, zTemp, nTemp);
-    sqlite3_free(zTemp);
+    if( zTemp ){
+      memcpy(zBuf, zTemp, nTemp);
+      sqlite3_free(zTemp);
+    }else{
+      assert( nTemp==0 );
+    }
 
     for(jj=0; jj<p->pPhrase->nToken; jj++){
       p->pPhrase->aToken[jj].z = zBuf;
@@ -727,7 +771,9 @@ exprparse_out:
 */
 int sqlite3Fts3ExprParse(
   sqlite3_tokenizer *pTokenizer,      /* Tokenizer module */
+  int iLangid,                        /* Language id for tokenizer */
   char **azCol,                       /* Array of column names for fts3 table */
+  int bFts4,                          /* True to allow FTS4-only syntax */
   int nCol,                           /* Number of entries in azCol[] */
   int iDefaultCol,                    /* Default column to query */
   const char *z, int n,               /* Text of MATCH query */
@@ -736,11 +782,14 @@ int sqlite3Fts3ExprParse(
   int nParsed;
   int rc;
   ParseContext sParse;
+
+  memset(&sParse, 0, sizeof(ParseContext));
   sParse.pTokenizer = pTokenizer;
+  sParse.iLangid = iLangid;
   sParse.azCol = (const char **)azCol;
   sParse.nCol = nCol;
   sParse.iDefaultCol = iDefaultCol;
-  sParse.nNest = 0;
+  sParse.bFts4 = bFts4;
   if( z==0 ){
     *ppExpr = 0;
     return SQLITE_OK;
@@ -930,7 +979,7 @@ static void fts3ExprTest(
   }
 
   rc = sqlite3Fts3ExprParse(
-      pTokenizer, azCol, nCol, nCol, zExpr, nExpr, &pExpr
+      pTokenizer, 0, azCol, 0, nCol, nCol, zExpr, nExpr, &pExpr
   );
   if( rc!=SQLITE_OK && rc!=SQLITE_NOMEM ){
     sqlite3_result_error(context, "Error parsing expression", -1);
diff --git a/src/libtracker-fts/fts3_icu.c b/src/libtracker-fts/fts3_icu.c
index a10a55d67..52df8c7d8 100644
--- a/src/libtracker-fts/fts3_icu.c
+++ b/src/libtracker-fts/fts3_icu.c
@@ -110,13 +110,16 @@ static int icuOpen(
 
   *ppCursor = 0;
 
-  if( nInput<0 ){
+  if( zInput==0 ){
+    nInput = 0;
+    zInput = "";
+  }else if( nInput<0 ){
     nInput = strlen(zInput);
   }
   nChar = nInput+1;
   pCsr = (IcuCursor *)sqlite3_malloc(
       sizeof(IcuCursor) +                /* IcuCursor */
-      nChar * sizeof(UChar) +            /* IcuCursor.aChar[] */
+      ((nChar+3)&~3) * sizeof(UChar) +   /* IcuCursor.aChar[] */
       (nChar+1) * sizeof(int)            /* IcuCursor.aOffset[] */
   );
   if( !pCsr ){
@@ -124,7 +127,7 @@ static int icuOpen(
   }
   memset(pCsr, 0, sizeof(IcuCursor));
   pCsr->aChar = (UChar *)&pCsr[1];
-  pCsr->aOffset = (int *)&pCsr->aChar[nChar];
+  pCsr->aOffset = (int *)&pCsr->aChar[(nChar+3)&~3];
 
   pCsr->aOffset[iOut] = iInput;
   U8_NEXT(zInput, iInput, nInput, c); 
@@ -196,7 +199,7 @@ static int icuNext(
 
     while( iStart<iEnd ){
       int iWhite = iStart;
-      U8_NEXT(pCsr->aChar, iWhite, pCsr->nChar, c);
+      U16_NEXT(pCsr->aChar, iWhite, pCsr->nChar, c);
       if( u_isspace(c) ){
         iStart = iWhite;
       }else{
diff --git a/src/libtracker-fts/fts3_porter.c b/src/libtracker-fts/fts3_porter.c
index 148c57008..579745b85 100644
--- a/src/libtracker-fts/fts3_porter.c
+++ b/src/libtracker-fts/fts3_porter.c
@@ -40,7 +40,7 @@ typedef struct porter_tokenizer {
 } porter_tokenizer;
 
 /*
-** Class derived from sqlit3_tokenizer_cursor
+** Class derived from sqlite3_tokenizer_cursor
 */
 typedef struct porter_tokenizer_cursor {
   sqlite3_tokenizer_cursor base;
@@ -630,6 +630,7 @@ static const sqlite3_tokenizer_module porterTokenizerModule = {
   porterOpen,
   porterClose,
   porterNext,
+  0
 };
 
 /*
diff --git a/src/libtracker-fts/fts3_snippet.c b/src/libtracker-fts/fts3_snippet.c
index b569eb131..4bee014dc 100644
--- a/src/libtracker-fts/fts3_snippet.c
+++ b/src/libtracker-fts/fts3_snippet.c
@@ -360,23 +360,27 @@ static int fts3SnippetFindPositions(Fts3Expr *pExpr, int iPhrase, void *ctx){
   SnippetIter *p = (SnippetIter *)ctx;
   SnippetPhrase *pPhrase = &p->aPhrase[iPhrase];
   char *pCsr;
+  int rc;
 
   pPhrase->nToken = pExpr->pPhrase->nToken;
-
-  pCsr = sqlite3Fts3EvalPhrasePoslist(p->pCsr, pExpr, p->iCol);
+  rc = sqlite3Fts3EvalPhrasePoslist(p->pCsr, pExpr, p->iCol, &pCsr);
+  assert( rc==SQLITE_OK || pCsr==0 );
   if( pCsr ){
     int iFirst = 0;
     pPhrase->pList = pCsr;
     fts3GetDeltaPosition(&pCsr, &iFirst);
+    assert( iFirst>=0 );
     pPhrase->pHead = pCsr;
     pPhrase->pTail = pCsr;
     pPhrase->iHead = iFirst;
     pPhrase->iTail = iFirst;
   }else{
-    assert( pPhrase->pList==0 && pPhrase->pHead==0 && pPhrase->pTail==0 );
+    assert( rc!=SQLITE_OK || (
+       pPhrase->pList==0 && pPhrase->pHead==0 && pPhrase->pTail==0 
+    ));
   }
 
-  return SQLITE_OK;
+  return rc;
 }
 
 /*
@@ -531,6 +535,7 @@ static int fts3StringAppend(
 */
 static int fts3SnippetShift(
   Fts3Table *pTab,                /* FTS3 table snippet comes from */
+  int iLangid,                    /* Language id to use in tokenizing */
   int nSnippet,                   /* Number of tokens desired for snippet */
   const char *zDoc,               /* Document text to extract snippet from */
   int nDoc,                       /* Size of buffer zDoc in bytes */
@@ -566,13 +571,12 @@ static int fts3SnippetShift(
       /* Open a cursor on zDoc/nDoc. Check if there are (nSnippet+nDesired)
       ** or more tokens in zDoc/nDoc.
       */
-      rc = pMod->xOpen(pTab->pTokenizer, zDoc, nDoc, &pC);
+      rc = sqlite3Fts3OpenTokenizer(pTab->pTokenizer, iLangid, zDoc, nDoc, &pC);
       if( rc!=SQLITE_OK ){
         return rc;
       }
-      pC->pTokenizer = pTab->pTokenizer;
       while( rc==SQLITE_OK && iCurrent<(nSnippet+nDesired) ){
-        const char *ZDUMMY; int DUMMY1, DUMMY2, DUMMY3;
+        const char *ZDUMMY; int DUMMY1 = 0, DUMMY2 = 0, DUMMY3 = 0;
         rc = pMod->xNext(pC, &ZDUMMY, &DUMMY1, &DUMMY2, &DUMMY3, &iCurrent);
       }
       pMod->xClose(pC);
@@ -616,8 +620,6 @@ static int fts3SnippetText(
   int iCol = pFragment->iCol+1;   /* Query column to extract text from */
   sqlite3_tokenizer_module *pMod; /* Tokenizer module methods object */
   sqlite3_tokenizer_cursor *pC;   /* Tokenizer cursor open on zDoc/nDoc */
-  const char *ZDUMMY;             /* Dummy argument used with tokenizer */
-  int DUMMY1;                     /* Dummy argument used with tokenizer */
   
   zDoc = (const char *)sqlite3_column_text(pCsr->pStmt, iCol);
   if( zDoc==0 ){
@@ -630,17 +632,29 @@ static int fts3SnippetText(
 
   /* Open a token cursor on the document. */
   pMod = (sqlite3_tokenizer_module *)pTab->pTokenizer->pModule;
-  rc = pMod->xOpen(pTab->pTokenizer, zDoc, nDoc, &pC);
+  rc = sqlite3Fts3OpenTokenizer(pTab->pTokenizer, pCsr->iLangid, zDoc,nDoc,&pC);
   if( rc!=SQLITE_OK ){
     return rc;
   }
-  pC->pTokenizer = pTab->pTokenizer;
 
   while( rc==SQLITE_OK ){
-    int iBegin;                   /* Offset in zDoc of start of token */
-    int iFin;                     /* Offset in zDoc of end of token */
-    int isHighlight;              /* True for highlighted terms */
-
+    const char *ZDUMMY;           /* Dummy argument used with tokenizer */
+    int DUMMY1 = -1;              /* Dummy argument used with tokenizer */
+    int iBegin = 0;               /* Offset in zDoc of start of token */
+    int iFin = 0;                 /* Offset in zDoc of end of token */
+    int isHighlight = 0;          /* True for highlighted terms */
+
+    /* Variable DUMMY1 is initialized to a negative value above. Elsewhere
+    ** in the FTS code the variable that the third argument to xNext points to
+    ** is initialized to zero before the first (*but not necessarily
+    ** subsequent*) call to xNext(). This is done for a particular application
+    ** that needs to know whether or not the tokenizer is being used for
+    ** snippet generation or for some other purpose.
+    **
+    ** Extreme care is required when writing code to depend on this
+    ** initialization. It is not a documented part of the tokenizer interface.
+    ** If a tokenizer is used directly by any code outside of FTS, this
+    ** convention might not be respected.  */
     rc = pMod->xNext(pC, &ZDUMMY, &DUMMY1, &iBegin, &iFin, &iCurrent);
     if( rc!=SQLITE_OK ){
       if( rc==SQLITE_DONE ){
@@ -656,7 +670,9 @@ static int fts3SnippetText(
 
     if( !isShiftDone ){
       int n = nDoc - iBegin;
-      rc = fts3SnippetShift(pTab, nSnippet, &zDoc[iBegin], n, &iPos, &hlmask);
+      rc = fts3SnippetShift(
+          pTab, pCsr->iLangid, nSnippet, &zDoc[iBegin], n, &iPos, &hlmask
+      );
       isShiftDone = 1;
 
       /* Now that the shift has been done, check if the initial "..." are
@@ -768,13 +784,14 @@ static int fts3ExprLocalHitsCb(
   int iPhrase,                    /* Phrase number */
   void *pCtx                      /* Pointer to MatchInfo structure */
 ){
+  int rc = SQLITE_OK;
   MatchInfo *p = (MatchInfo *)pCtx;
   int iStart = iPhrase * p->nCol * 3;
   int i;
 
-  for(i=0; i<p->nCol; i++){
+  for(i=0; i<p->nCol && rc==SQLITE_OK; i++){
     char *pCsr;
-    pCsr = sqlite3Fts3EvalPhrasePoslist(p->pCursor, pExpr, i);
+    rc = sqlite3Fts3EvalPhrasePoslist(p->pCursor, pExpr, i, &pCsr);
     if( pCsr ){
       p->aMatchinfo[iStart+i*3] = fts3ColumnlistCount(&pCsr);
     }else{
@@ -782,7 +799,7 @@ static int fts3ExprLocalHitsCb(
     }
   }
 
-  return SQLITE_OK;
+  return rc;
 }
 
 static int fts3MatchinfoCheck(
@@ -792,8 +809,8 @@ static int fts3MatchinfoCheck(
 ){
   if( (cArg==FTS3_MATCHINFO_NPHRASE)
    || (cArg==FTS3_MATCHINFO_NCOL)
-   || (cArg==FTS3_MATCHINFO_NDOC && pTab->bHasStat)
-   || (cArg==FTS3_MATCHINFO_AVGLENGTH && pTab->bHasStat)
+   || (cArg==FTS3_MATCHINFO_NDOC && pTab->bFts4)
+   || (cArg==FTS3_MATCHINFO_AVGLENGTH && pTab->bFts4)
    || (cArg==FTS3_MATCHINFO_LENGTH && pTab->bHasDocsize)
    || (cArg==FTS3_MATCHINFO_LCS)
    || (cArg==FTS3_MATCHINFO_HITS)
@@ -848,7 +865,7 @@ static int fts3MatchinfoSelectDoctotal(
 
   a = sqlite3_column_blob(pStmt, 0);
   a += sqlite3Fts3GetVarint(a, &nDoc);
-  if( nDoc==0 ) return SQLITE_CORRUPT_VTAB;
+  if( nDoc==0 ) return FTS_CORRUPT_VTAB;
   *pnDoc = (u32)nDoc;
 
   if( paLen ) *paLen = a;
@@ -943,8 +960,10 @@ static int fts3MatchinfoLcs(Fts3Cursor *pCsr, MatchInfo *pInfo){
     int nLive = 0;                /* Number of iterators in aIter not at EOF */
 
     for(i=0; i<pInfo->nPhrase; i++){
+      int rc;
       LcsIterator *pIt = &aIter[i];
-      pIt->pRead = sqlite3Fts3EvalPhrasePoslist(pCsr, pIt->pExpr, iCol);
+      rc = sqlite3Fts3EvalPhrasePoslist(pCsr, pIt->pExpr, iCol, &pIt->pRead);
+      if( rc!=SQLITE_OK ) return rc;
       if( pIt->pRead ){
         pIt->iPos = pIt->iPosOffset;
         fts3LcsIteratorAdvance(&aIter[i]);
@@ -1296,9 +1315,10 @@ static int fts3ExprTermOffsetInit(Fts3Expr *pExpr, int iPhrase, void *ctx){
   int iTerm;                      /* For looping through nTerm phrase terms */
   char *pList;                    /* Pointer to position list for phrase */
   int iPos = 0;                   /* First position in position-list */
+  int rc;
 
   UNUSED_PARAMETER(iPhrase);
-  pList = sqlite3Fts3EvalPhrasePoslist(p->pCsr, pExpr, p->iCol);
+  rc = sqlite3Fts3EvalPhrasePoslist(p->pCsr, pExpr, p->iCol, &pList);
   nTerm = pExpr->pPhrase->nToken;
   if( pList ){
     fts3GetDeltaPosition(&pList, &iPos);
@@ -1312,7 +1332,7 @@ static int fts3ExprTermOffsetInit(Fts3Expr *pExpr, int iPhrase, void *ctx){
     pT->iPos = iPos;
   }
 
-  return SQLITE_OK;
+  return rc;
 }
 
 /*
@@ -1324,8 +1344,6 @@ void sqlite3Fts3Offsets(
 ){
   Fts3Table *pTab = (Fts3Table *)pCsr->base.pVtab;
   sqlite3_tokenizer_module const *pMod = pTab->pTokenizer->pModule;
-  const char *ZDUMMY;             /* Dummy argument used with xNext() */
-  int NDUMMY;                     /* Dummy argument used with xNext() */
   int rc;                         /* Return Code */
   int nToken;                     /* Number of tokens in query */
   int iCol;                       /* Column currently being processed */
@@ -1358,9 +1376,11 @@ void sqlite3Fts3Offsets(
   */
   for(iCol=0; iCol<pTab->nColumn; iCol++){
     sqlite3_tokenizer_cursor *pC; /* Tokenizer cursor */
-    int iStart;
-    int iEnd;
-    int iCurrent;
+    const char *ZDUMMY;           /* Dummy argument used with xNext() */
+    int NDUMMY = 0;               /* Dummy argument used with xNext() */
+    int iStart = 0;
+    int iEnd = 0;
+    int iCurrent = 0;
     const char *zDoc;
     int nDoc;
 
@@ -1389,9 +1409,10 @@ void sqlite3Fts3Offsets(
     }
 
     /* Initialize a tokenizer iterator to iterate through column iCol. */
-    rc = pMod->xOpen(pTab->pTokenizer, zDoc, nDoc, &pC);
+    rc = sqlite3Fts3OpenTokenizer(pTab->pTokenizer, pCsr->iLangid,
+        zDoc, nDoc, &pC
+    );
     if( rc!=SQLITE_OK ) goto offsets_out;
-    pC->pTokenizer = pTab->pTokenizer;
 
     rc = pMod->xNext(pC, &ZDUMMY, &NDUMMY, &iStart, &iEnd, &iCurrent);
     while( rc==SQLITE_OK ){
@@ -1409,7 +1430,7 @@ void sqlite3Fts3Offsets(
 
       if( !pTerm ){
         /* All offsets for this column have been gathered. */
-        break;
+        rc = SQLITE_DONE;
       }else{
         assert( iCurrent<=iMinPos );
         if( 0==(0xFE&*pTerm->pList) ){
@@ -1426,8 +1447,8 @@ void sqlite3Fts3Offsets(
               "%d %d %d %d ", iCol, pTerm-sCtx.aTerm, iStart, iEnd-iStart
           );
           rc = fts3StringAppend(&res, aBuffer, -1);
-        }else if( rc==SQLITE_DONE ){
-          rc = SQLITE_CORRUPT_VTAB;
+        }else if( rc==SQLITE_DONE && pTab->zContentTbl==0 ){
+          rc = FTS_CORRUPT_VTAB;
         }
       }
     }
diff --git a/src/libtracker-fts/fts3_term.c b/src/libtracker-fts/fts3_term.c
index d3eb690bd..c49d5cb65 100644
--- a/src/libtracker-fts/fts3_term.c
+++ b/src/libtracker-fts/fts3_term.c
@@ -73,6 +73,7 @@ static int fts3termConnectMethod(
   Fts3termTable *p;                /* Virtual table object to return */
   int iIndex = 0;
 
+  UNUSED_PARAMETER(pCtx);
   if( argc==5 ){
     iIndex = atoi(argv[4]);
     argc--;
@@ -87,9 +88,9 @@ static int fts3termConnectMethod(
   }
 
   zDb = argv[1]; 
-  nDb = strlen(zDb);
+  nDb = (int)strlen(zDb);
   zFts3 = argv[3];
-  nFts3 = strlen(zFts3);
+  nFts3 = (int)strlen(zFts3);
 
   rc = sqlite3_declare_vtab(db, FTS3_TERMS_SCHEMA);
   if( rc!=SQLITE_OK ) return rc;
@@ -231,12 +232,12 @@ static int fts3termNextMethod(sqlite3_vtab_cursor *pCursor){
 
   if( v==1 ){
     pCsr->pNext += sqlite3Fts3GetVarint(pCsr->pNext, &v);
-    pCsr->iCol += v;
+    pCsr->iCol += (int)v;
     pCsr->iPos = 0;
     pCsr->pNext += sqlite3Fts3GetVarint(pCsr->pNext, &v);
   }
 
-  pCsr->iPos += (v - 2);
+  pCsr->iPos += (int)(v - 2);
 
   return SQLITE_OK;
 }
@@ -271,7 +272,7 @@ static int fts3termFilterMethod(
   pCsr->filter.flags = FTS3_SEGMENT_REQUIRE_POS|FTS3_SEGMENT_IGNORE_EMPTY;
   pCsr->filter.flags |= FTS3_SEGMENT_SCAN;
 
-  rc = sqlite3Fts3SegReaderCursor(pFts3, p->iIndex, FTS3_SEGCURSOR_ALL,
+  rc = sqlite3Fts3SegReaderCursor(pFts3, 0, p->iIndex, FTS3_SEGCURSOR_ALL,
       pCsr->filter.zTerm, pCsr->filter.nTerm, 0, 1, &pCsr->csr
   );
   if( rc==SQLITE_OK ){
@@ -357,7 +358,10 @@ int sqlite3Fts3InitTerm(sqlite3 *db){
      0,                           /* xCommit       */
      0,                           /* xRollback     */
      0,                           /* xFindFunction */
-     0                            /* xRename       */
+     0,                           /* xRename       */
+     0,                           /* xSavepoint    */
+     0,                           /* xRelease      */
+     0                            /* xRollbackTo   */
   };
   int rc;                         /* Return code */
 
diff --git a/src/libtracker-fts/fts3_test.c b/src/libtracker-fts/fts3_test.c
index 72735f3d1..4da0b8f13 100644
--- a/src/libtracker-fts/fts3_test.c
+++ b/src/libtracker-fts/fts3_test.c
@@ -13,13 +13,17 @@
 ** This file is not part of the production FTS code. It is only used for
 ** testing. It contains a Tcl command that can be used to test if a document
 ** matches an FTS NEAR expression.
+**
+** As of March 2012, it also contains a version 1 tokenizer used for testing
+** that the sqlite3_tokenizer_module.xLanguage() method is invoked correctly.
 */
 
 #include <tcl.h>
 #include <string.h>
 #include <assert.h>
 
-#ifdef SQLITE_TEST
+#if defined(SQLITE_TEST)
+#if defined(SQLITE_ENABLE_FTS3) || defined(SQLITE_ENABLE_FTS4)
 
 /* Required so that the "ifdef SQLITE_ENABLE_FTS3" below works */
 #include "fts3Int.h"
@@ -158,6 +162,8 @@ static int fts3_near_match_cmd(
   Tcl_Obj **apExprToken;
   int nExprToken;
 
+  UNUSED_PARAMETER(clientData);
+
   /* Must have 3 or more arguments. */
   if( objc<3 || (objc%2)==0 ){
     Tcl_WrongNumArgs(interp, 1, objv, "DOCUMENT EXPR ?OPTION VALUE?...");
@@ -311,14 +317,219 @@ static int fts3_configure_incr_load_cmd(
   Tcl_SetObjResult(interp, pRet);
   Tcl_DecrRefCount(pRet);
 #endif
+  UNUSED_PARAMETER(clientData);
+  return TCL_OK;
+}
+
+#ifdef SQLITE_ENABLE_FTS3
+/**************************************************************************
+** Beginning of test tokenizer code.
+**
+** For language 0, this tokenizer is similar to the default 'simple' 
+** tokenizer. For other languages L, the following:
+**
+**   * Odd numbered languages are case-sensitive. Even numbered 
+**     languages are not.
+**
+**   * Language ids 100 or greater are considered an error.
+**
+** The implementation assumes that the input contains only ASCII characters
+** (i.e. those that may be encoded in UTF-8 using a single byte).
+*/
+typedef struct test_tokenizer {
+  sqlite3_tokenizer base;
+} test_tokenizer;
+
+typedef struct test_tokenizer_cursor {
+  sqlite3_tokenizer_cursor base;
+  const char *aInput;          /* Input being tokenized */
+  int nInput;                  /* Size of the input in bytes */
+  int iInput;                  /* Current offset in aInput */
+  int iToken;                  /* Index of next token to be returned */
+  char *aBuffer;               /* Buffer containing current token */
+  int nBuffer;                 /* Number of bytes allocated at pToken */
+  int iLangid;                 /* Configured language id */
+} test_tokenizer_cursor;
+
+static int testTokenizerCreate(
+  int argc, const char * const *argv,
+  sqlite3_tokenizer **ppTokenizer
+){
+  test_tokenizer *pNew;
+  UNUSED_PARAMETER(argc);
+  UNUSED_PARAMETER(argv);
+
+  pNew = sqlite3_malloc(sizeof(test_tokenizer));
+  if( !pNew ) return SQLITE_NOMEM;
+  memset(pNew, 0, sizeof(test_tokenizer));
+
+  *ppTokenizer = (sqlite3_tokenizer *)pNew;
+  return SQLITE_OK;
+}
+
+static int testTokenizerDestroy(sqlite3_tokenizer *pTokenizer){
+  test_tokenizer *p = (test_tokenizer *)pTokenizer;
+  sqlite3_free(p);
+  return SQLITE_OK;
+}
+
+static int testTokenizerOpen(
+  sqlite3_tokenizer *pTokenizer,         /* The tokenizer */
+  const char *pInput, int nBytes,        /* String to be tokenized */
+  sqlite3_tokenizer_cursor **ppCursor    /* OUT: Tokenization cursor */
+){
+  int rc = SQLITE_OK;                    /* Return code */
+  test_tokenizer_cursor *pCsr;           /* New cursor object */
+
+  UNUSED_PARAMETER(pTokenizer);
+
+  pCsr = (test_tokenizer_cursor *)sqlite3_malloc(sizeof(test_tokenizer_cursor));
+  if( pCsr==0 ){
+    rc = SQLITE_NOMEM;
+  }else{
+    memset(pCsr, 0, sizeof(test_tokenizer_cursor));
+    pCsr->aInput = pInput;
+    if( nBytes<0 ){
+      pCsr->nInput = (int)strlen(pInput);
+    }else{
+      pCsr->nInput = nBytes;
+    }
+  }
+
+  *ppCursor = (sqlite3_tokenizer_cursor *)pCsr;
+  return rc;
+}
+
+static int testTokenizerClose(sqlite3_tokenizer_cursor *pCursor){
+  test_tokenizer_cursor *pCsr = (test_tokenizer_cursor *)pCursor;
+  sqlite3_free(pCsr->aBuffer);
+  sqlite3_free(pCsr);
+  return SQLITE_OK;
+}
+
+static int testIsTokenChar(char c){
+  return (c>='a' && c<='z') || (c>='A' && c<='Z');
+}
+static int testTolower(char c){
+  char ret = c;
+  if( ret>='A' && ret<='Z') ret = ret - ('A'-'a');
+  return ret;
+}
+
+static int testTokenizerNext(
+  sqlite3_tokenizer_cursor *pCursor,  /* Cursor returned by testTokenizerOpen */
+  const char **ppToken,               /* OUT: *ppToken is the token text */
+  int *pnBytes,                       /* OUT: Number of bytes in token */
+  int *piStartOffset,                 /* OUT: Starting offset of token */
+  int *piEndOffset,                   /* OUT: Ending offset of token */
+  int *piPosition                     /* OUT: Position integer of token */
+){
+  test_tokenizer_cursor *pCsr = (test_tokenizer_cursor *)pCursor;
+  int rc = SQLITE_OK;
+  const char *p;
+  const char *pEnd;
+
+  p = &pCsr->aInput[pCsr->iInput];
+  pEnd = &pCsr->aInput[pCsr->nInput];
+
+  /* Skip past any white-space */
+  assert( p<=pEnd );
+  while( p<pEnd && testIsTokenChar(*p)==0 ) p++;
+
+  if( p==pEnd ){
+    rc = SQLITE_DONE;
+  }else{
+    /* Advance to the end of the token */
+    const char *pToken = p;
+    int nToken;
+    while( p<pEnd && testIsTokenChar(*p) ) p++;
+    nToken = (int)(p-pToken);
+
+    /* Copy the token into the buffer */
+    if( nToken>pCsr->nBuffer ){
+      sqlite3_free(pCsr->aBuffer);
+      pCsr->aBuffer = sqlite3_malloc(nToken);
+    }
+    if( pCsr->aBuffer==0 ){
+      rc = SQLITE_NOMEM;
+    }else{
+      int i;
+
+      if( pCsr->iLangid & 0x00000001 ){
+        for(i=0; i<nToken; i++) pCsr->aBuffer[i] = pToken[i];
+      }else{
+        for(i=0; i<nToken; i++) pCsr->aBuffer[i] = testTolower(pToken[i]);
+      }
+      pCsr->iToken++;
+      pCsr->iInput = (int)(p - pCsr->aInput);
+
+      *ppToken = pCsr->aBuffer;
+      *pnBytes = nToken;
+      *piStartOffset = (int)(pToken - pCsr->aInput);
+      *piEndOffset = (int)(p - pCsr->aInput);
+      *piPosition = pCsr->iToken;
+    }
+  }
+
+  return rc;
+}
+
+static int testTokenizerLanguage(
+  sqlite3_tokenizer_cursor *pCursor,
+  int iLangid
+){
+  int rc = SQLITE_OK;
+  test_tokenizer_cursor *pCsr = (test_tokenizer_cursor *)pCursor;
+  pCsr->iLangid = iLangid;
+  if( pCsr->iLangid>=100 ){
+    rc = SQLITE_ERROR;
+  }
+  return rc;
+}
+#endif
+
+static int fts3_test_tokenizer_cmd(
+  ClientData clientData,
+  Tcl_Interp *interp,
+  int objc,
+  Tcl_Obj *CONST objv[]
+){
+#ifdef SQLITE_ENABLE_FTS3
+  static const sqlite3_tokenizer_module testTokenizerModule = {
+    1,
+    testTokenizerCreate,
+    testTokenizerDestroy,
+    testTokenizerOpen,
+    testTokenizerClose,
+    testTokenizerNext,
+    testTokenizerLanguage
+  };
+  const sqlite3_tokenizer_module *pPtr = &testTokenizerModule;
+  if( objc!=1 ){
+    Tcl_WrongNumArgs(interp, 1, objv, "");
+    return TCL_ERROR;
+  }
+  Tcl_SetObjResult(interp, Tcl_NewByteArrayObj(
+    (const unsigned char *)&pPtr, sizeof(sqlite3_tokenizer_module *)
+  ));
+#endif
+  UNUSED_PARAMETER(clientData);
   return TCL_OK;
 }
 
+/* 
+** End of tokenizer code.
+**************************************************************************/ 
+
 int Sqlitetestfts3_Init(Tcl_Interp *interp){
   Tcl_CreateObjCommand(interp, "fts3_near_match", fts3_near_match_cmd, 0, 0);
   Tcl_CreateObjCommand(interp, 
       "fts3_configure_incr_load", fts3_configure_incr_load_cmd, 0, 0
   );
+  Tcl_CreateObjCommand(
+      interp, "fts3_test_tokenizer", fts3_test_tokenizer_cmd, 0, 0
+  );
   return TCL_OK;
 }
+#endif                  /* SQLITE_ENABLE_FTS3 || SQLITE_ENABLE_FTS4 */
 #endif                  /* ifdef SQLITE_TEST */
diff --git a/src/libtracker-fts/fts3_tokenizer.c b/src/libtracker-fts/fts3_tokenizer.c
index 6494bb96d..8241be81f 100644
--- a/src/libtracker-fts/fts3_tokenizer.c
+++ b/src/libtracker-fts/fts3_tokenizer.c
@@ -209,10 +209,9 @@ int sqlite3Fts3InitTokenizer(
 /*
 ** Implementation of a special SQL scalar function for testing tokenizers 
 ** designed to be used in concert with the Tcl testing framework. This
-** function must be called with two arguments:
+** function must be called with two or more arguments:
 **
-**   SELECT <function-name>(<key-name>, <input-string>);
-**   SELECT <function-name>(<key-name>, <pointer>);
+**   SELECT <function-name>(<key-name>, ..., <input-string>);
 **
 ** where <function-name> is the name passed as the second argument
 ** to the sqlite3Fts3InitHashTable() function (e.g. 'fts3_tokenizer')
@@ -249,27 +248,27 @@ static void testFunc(
   const char *zInput;
   int nInput;
 
-  const char *zArg = 0;
+  const char *azArg[64];
 
   const char *zToken;
-  int nToken;
-  int iStart;
-  int iEnd;
-  int iPos;
+  int nToken = 0;
+  int iStart = 0;
+  int iEnd = 0;
+  int iPos = 0;
+  int i;
 
   Tcl_Obj *pRet;
 
-  assert( argc==2 || argc==3 );
+  if( argc<2 ){
+    sqlite3_result_error(context, "insufficient arguments", -1);
+    return;
+  }
 
   nName = sqlite3_value_bytes(argv[0]);
   zName = (const char *)sqlite3_value_text(argv[0]);
   nInput = sqlite3_value_bytes(argv[argc-1]);
   zInput = (const char *)sqlite3_value_text(argv[argc-1]);
 
-  if( argc==3 ){
-    zArg = (const char *)sqlite3_value_text(argv[1]);
-  }
-
   pHash = (Fts3Hash *)sqlite3_user_data(context);
   p = (sqlite3_tokenizer_module *)sqlite3Fts3HashFind(pHash, zName, nName+1);
 
@@ -283,16 +282,19 @@ static void testFunc(
   pRet = Tcl_NewObj();
   Tcl_IncrRefCount(pRet);
 
-  if( SQLITE_OK!=p->xCreate(zArg ? 1 : 0, &zArg, &pTokenizer) ){
+  for(i=1; i<argc-1; i++){
+    azArg[i-1] = (const char *)sqlite3_value_text(argv[i]);
+  }
+
+  if( SQLITE_OK!=p->xCreate(argc-2, azArg, &pTokenizer) ){
     zErr = "error in xCreate()";
     goto finish;
   }
   pTokenizer->pModule = p;
-  if( SQLITE_OK!=p->xOpen(pTokenizer, zInput, nInput, &pCsr) ){
+  if( sqlite3Fts3OpenTokenizer(pTokenizer, 0, zInput, nInput, &pCsr) ){
     zErr = "error in xOpen()";
     goto finish;
   }
-  pCsr->pTokenizer = pTokenizer;
 
   while( SQLITE_OK==p->xNext(pCsr, &zToken, &nToken, &iStart, &iEnd, &iPos) ){
     Tcl_ListObjAppendElement(0, pRet, Tcl_NewIntObj(iPos));
@@ -468,10 +470,7 @@ int sqlite3Fts3InitHashTable(
   }
 #ifdef SQLITE_TEST
   if( SQLITE_OK==rc ){
-    rc = sqlite3_create_function(db, zTest, 2, any, p, testFunc, 0, 0);
-  }
-  if( SQLITE_OK==rc ){
-    rc = sqlite3_create_function(db, zTest, 3, any, p, testFunc, 0, 0);
+    rc = sqlite3_create_function(db, zTest, -1, any, p, testFunc, 0, 0);
   }
   if( SQLITE_OK==rc ){
     rc = sqlite3_create_function(db, zTest2, 0, any, pdb, intTestFunc, 0, 0);
diff --git a/src/libtracker-fts/fts3_tokenizer.h b/src/libtracker-fts/fts3_tokenizer.h
index 615644506..c91c7ed79 100644
--- a/src/libtracker-fts/fts3_tokenizer.h
+++ b/src/libtracker-fts/fts3_tokenizer.h
@@ -52,7 +52,7 @@ typedef struct sqlite3_tokenizer_cursor sqlite3_tokenizer_cursor;
 struct sqlite3_tokenizer_module {
 
   /*
-  ** Structure version. Should always be set to 0.
+  ** Structure version. Should always be set to 0 or 1.
   */
   int iVersion;
 
@@ -133,6 +133,15 @@ struct sqlite3_tokenizer_module {
     int *piEndOffset,    /* OUT: Byte offset of end of token in input buffer */
     int *piPosition      /* OUT: Number of tokens returned before this one */
   );
+
+  /***********************************************************************
+  ** Methods below this point are only available if iVersion>=1.
+  */
+
+  /* 
+  ** Configure the language id of a tokenizer cursor.
+  */
+  int (*xLanguageid)(sqlite3_tokenizer_cursor *pCsr, int iLangid);
 };
 
 struct sqlite3_tokenizer {
diff --git a/src/libtracker-fts/fts3_tokenizer1.c b/src/libtracker-fts/fts3_tokenizer1.c
index d11a49976..deea06d92 100644
--- a/src/libtracker-fts/fts3_tokenizer1.c
+++ b/src/libtracker-fts/fts3_tokenizer1.c
@@ -218,6 +218,7 @@ static const sqlite3_tokenizer_module simpleTokenizerModule = {
   simpleOpen,
   simpleClose,
   simpleNext,
+  0,
 };
 
 /*
diff --git a/src/libtracker-fts/fts3_unicode.c b/src/libtracker-fts/fts3_unicode.c
new file mode 100644
index 000000000..79941edbb
--- /dev/null
+++ b/src/libtracker-fts/fts3_unicode.c
@@ -0,0 +1,393 @@
+/*
+** 2012 May 24
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** Implementation of the "unicode" full-text-search tokenizer.
+*/
+
+#ifdef SQLITE_ENABLE_FTS4_UNICODE61
+
+#include "fts3Int.h"
+#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)
+
+#include <assert.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "fts3_tokenizer.h"
+
+/*
+** The following two macros - READ_UTF8 and WRITE_UTF8 - have been copied
+** from the sqlite3 source file utf.c. If this file is compiled as part
+** of the amalgamation, they are not required.
+*/
+#ifndef SQLITE_AMALGAMATION
+
+static const unsigned char sqlite3Utf8Trans1[] = {
+  0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+  0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
+  0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
+  0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
+  0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+  0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
+  0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+  0x00, 0x01, 0x02, 0x03, 0x00, 0x01, 0x00, 0x00,
+};
+
+#define READ_UTF8(zIn, zTerm, c)                           \
+  c = *(zIn++);                                            \
+  if( c>=0xc0 ){                                           \
+    c = sqlite3Utf8Trans1[c-0xc0];                         \
+    while( zIn!=zTerm && (*zIn & 0xc0)==0x80 ){            \
+      c = (c<<6) + (0x3f & *(zIn++));                      \
+    }                                                      \
+    if( c<0x80                                             \
+        || (c&0xFFFFF800)==0xD800                          \
+        || (c&0xFFFFFFFE)==0xFFFE ){  c = 0xFFFD; }        \
+  }
+
+#define WRITE_UTF8(zOut, c) {                          \
+  if( c<0x00080 ){                                     \
+    *zOut++ = (u8)(c&0xFF);                            \
+  }                                                    \
+  else if( c<0x00800 ){                                \
+    *zOut++ = 0xC0 + (u8)((c>>6)&0x1F);                \
+    *zOut++ = 0x80 + (u8)(c & 0x3F);                   \
+  }                                                    \
+  else if( c<0x10000 ){                                \
+    *zOut++ = 0xE0 + (u8)((c>>12)&0x0F);               \
+    *zOut++ = 0x80 + (u8)((c>>6) & 0x3F);              \
+    *zOut++ = 0x80 + (u8)(c & 0x3F);                   \
+  }else{                                               \
+    *zOut++ = 0xF0 + (u8)((c>>18) & 0x07);             \
+    *zOut++ = 0x80 + (u8)((c>>12) & 0x3F);             \
+    *zOut++ = 0x80 + (u8)((c>>6) & 0x3F);              \
+    *zOut++ = 0x80 + (u8)(c & 0x3F);                   \
+  }                                                    \
+}
+
+#endif /* ifndef SQLITE_AMALGAMATION */
+
+typedef struct unicode_tokenizer unicode_tokenizer;
+typedef struct unicode_cursor unicode_cursor;
+
+struct unicode_tokenizer {
+  sqlite3_tokenizer base;
+  int bRemoveDiacritic;
+  int nException;
+  int *aiException;
+};
+
+struct unicode_cursor {
+  sqlite3_tokenizer_cursor base;
+  const unsigned char *aInput;    /* Input text being tokenized */
+  int nInput;                     /* Size of aInput[] in bytes */
+  int iOff;                       /* Current offset within aInput[] */
+  int iToken;                     /* Index of next token to be returned */
+  char *zToken;                   /* storage for current token */
+  int nAlloc;                     /* space allocated at zToken */
+};
+
+
+/*
+** Destroy a tokenizer allocated by unicodeCreate().
+*/
+static int unicodeDestroy(sqlite3_tokenizer *pTokenizer){
+  if( pTokenizer ){
+    unicode_tokenizer *p = (unicode_tokenizer *)pTokenizer;
+    sqlite3_free(p->aiException);
+    sqlite3_free(p);
+  }
+  return SQLITE_OK;
+}
+
+/*
+** As part of a tokenchars= or separators= option, the CREATE VIRTUAL TABLE
+** statement has specified that the tokenizer for this table shall consider
+** all characters in string zIn/nIn to be separators (if bAlnum==0) or
+** token characters (if bAlnum==1).
+**
+** For each codepoint in the zIn/nIn string, this function checks if the
+** sqlite3FtsUnicodeIsalnum() function already returns the desired result.
+** If so, no action is taken. Otherwise, the codepoint is added to the 
+** unicode_tokenizer.aiException[] array. For the purposes of tokenization,
+** the return value of sqlite3FtsUnicodeIsalnum() is inverted for all
+** codepoints in the aiException[] array.
+**
+** If a standalone diacritic mark (one that sqlite3FtsUnicodeIsdiacritic()
+** identifies as a diacritic) occurs in the zIn/nIn string it is ignored.
+** It is not possible to change the behaviour of the tokenizer with respect
+** to these codepoints.
+*/
+static int unicodeAddExceptions(
+  unicode_tokenizer *p,           /* Tokenizer to add exceptions to */
+  int bAlnum,                     /* Replace Isalnum() return value with this */
+  const char *zIn,                /* Array of characters to make exceptions */
+  int nIn                         /* Length of z in bytes */
+){
+  const unsigned char *z = (const unsigned char *)zIn;
+  const unsigned char *zTerm = &z[nIn];
+  int iCode;
+  int nEntry = 0;
+
+  assert( bAlnum==0 || bAlnum==1 );
+
+  while( z<zTerm ){
+    READ_UTF8(z, zTerm, iCode);
+    assert( (sqlite3FtsUnicodeIsalnum(iCode) & 0xFFFFFFFE)==0 );
+    if( sqlite3FtsUnicodeIsalnum(iCode)!=bAlnum 
+     && sqlite3FtsUnicodeIsdiacritic(iCode)==0 
+    ){
+      nEntry++;
+    }
+  }
+
+  if( nEntry ){
+    int *aNew;                    /* New aiException[] array */
+    int nNew;                     /* Number of valid entries in array aNew[] */
+
+    aNew = sqlite3_realloc(p->aiException, (p->nException+nEntry)*sizeof(int));
+    if( aNew==0 ) return SQLITE_NOMEM;
+    nNew = p->nException;
+
+    z = (const unsigned char *)zIn;
+    while( z<zTerm ){
+      READ_UTF8(z, zTerm, iCode);
+      if( sqlite3FtsUnicodeIsalnum(iCode)!=bAlnum 
+       && sqlite3FtsUnicodeIsdiacritic(iCode)==0
+      ){
+        int i, j;
+        for(i=0; i<nNew && aNew[i]<iCode; i++);
+        for(j=nNew; j>i; j--) aNew[j] = aNew[j-1];
+        aNew[i] = iCode;
+        nNew++;
+      }
+    }
+    p->aiException = aNew;
+    p->nException = nNew;
+  }
+
+  return SQLITE_OK;
+}
+
+/*
+** Return true if the p->aiException[] array contains the value iCode.
+*/
+static int unicodeIsException(unicode_tokenizer *p, int iCode){
+  if( p->nException>0 ){
+    int *a = p->aiException;
+    int iLo = 0;
+    int iHi = p->nException-1;
+
+    while( iHi>=iLo ){
+      int iTest = (iHi + iLo) / 2;
+      if( iCode==a[iTest] ){
+        return 1;
+      }else if( iCode>a[iTest] ){
+        iLo = iTest+1;
+      }else{
+        iHi = iTest-1;
+      }
+    }
+  }
+
+  return 0;
+}
+
+/*
+** Return true if, for the purposes of tokenization, codepoint iCode is
+** considered a token character (not a separator).
+*/
+static int unicodeIsAlnum(unicode_tokenizer *p, int iCode){
+  assert( (sqlite3FtsUnicodeIsalnum(iCode) & 0xFFFFFFFE)==0 );
+  return sqlite3FtsUnicodeIsalnum(iCode) ^ unicodeIsException(p, iCode);
+}
+
+/*
+** Create a new tokenizer instance.
+*/
+static int unicodeCreate(
+  int nArg,                       /* Size of array argv[] */
+  const char * const *azArg,      /* Tokenizer creation arguments */
+  sqlite3_tokenizer **pp          /* OUT: New tokenizer handle */
+){
+  unicode_tokenizer *pNew;        /* New tokenizer object */
+  int i;
+  int rc = SQLITE_OK;
+
+  pNew = (unicode_tokenizer *) sqlite3_malloc(sizeof(unicode_tokenizer));
+  if( pNew==NULL ) return SQLITE_NOMEM;
+  memset(pNew, 0, sizeof(unicode_tokenizer));
+  pNew->bRemoveDiacritic = 1;
+
+  for(i=0; rc==SQLITE_OK && i<nArg; i++){
+    const char *z = azArg[i];
+    int n = strlen(z);
+
+    if( n==19 && memcmp("remove_diacritics=1", z, 19)==0 ){
+      pNew->bRemoveDiacritic = 1;
+    }
+    else if( n==19 && memcmp("remove_diacritics=0", z, 19)==0 ){
+      pNew->bRemoveDiacritic = 0;
+    }
+    else if( n>=11 && memcmp("tokenchars=", z, 11)==0 ){
+      rc = unicodeAddExceptions(pNew, 1, &z[11], n-11);
+    }
+    else if( n>=11 && memcmp("separators=", z, 11)==0 ){
+      rc = unicodeAddExceptions(pNew, 0, &z[11], n-11);
+    }
+    else{
+      /* Unrecognized argument */
+      rc  = SQLITE_ERROR;
+    }
+  }
+
+  if( rc!=SQLITE_OK ){
+    unicodeDestroy((sqlite3_tokenizer *)pNew);
+    pNew = 0;
+  }
+  *pp = (sqlite3_tokenizer *)pNew;
+  return rc;
+}
+
+/*
+** Prepare to begin tokenizing a particular string.  The input
+** string to be tokenized is pInput[0..nBytes-1].  A cursor
+** used to incrementally tokenize this string is returned in 
+** *ppCursor.
+*/
+static int unicodeOpen(
+  sqlite3_tokenizer *p,           /* The tokenizer */
+  const char *aInput,             /* Input string */
+  int nInput,                     /* Size of string aInput in bytes */
+  sqlite3_tokenizer_cursor **pp   /* OUT: New cursor object */
+){
+  unicode_cursor *pCsr;
+
+  pCsr = (unicode_cursor *)sqlite3_malloc(sizeof(unicode_cursor));
+  if( pCsr==0 ){
+    return SQLITE_NOMEM;
+  }
+  memset(pCsr, 0, sizeof(unicode_cursor));
+
+  pCsr->aInput = (const unsigned char *)aInput;
+  if( aInput==0 ){
+    pCsr->nInput = 0;
+  }else if( nInput<0 ){
+    pCsr->nInput = (int)strlen(aInput);
+  }else{
+    pCsr->nInput = nInput;
+  }
+
+  *pp = &pCsr->base;
+  UNUSED_PARAMETER(p);
+  return SQLITE_OK;
+}
+
+/*
+** Close a tokenization cursor previously opened by a call to
+** simpleOpen() above.
+*/
+static int unicodeClose(sqlite3_tokenizer_cursor *pCursor){
+  unicode_cursor *pCsr = (unicode_cursor *) pCursor;
+  sqlite3_free(pCsr->zToken);
+  sqlite3_free(pCsr);
+  return SQLITE_OK;
+}
+
+/*
+** Extract the next token from a tokenization cursor.  The cursor must
+** have been opened by a prior call to simpleOpen().
+*/
+static int unicodeNext(
+  sqlite3_tokenizer_cursor *pC,   /* Cursor returned by simpleOpen */
+  const char **paToken,           /* OUT: Token text */
+  int *pnToken,                   /* OUT: Number of bytes at *paToken */
+  int *piStart,                   /* OUT: Starting offset of token */
+  int *piEnd,                     /* OUT: Ending offset of token */
+  int *piPos                      /* OUT: Position integer of token */
+){
+  unicode_cursor *pCsr = (unicode_cursor *)pC;
+  unicode_tokenizer *p = ((unicode_tokenizer *)pCsr->base.pTokenizer);
+  int iCode;
+  char *zOut;
+  const unsigned char *z = &pCsr->aInput[pCsr->iOff];
+  const unsigned char *zStart = z;
+  const unsigned char *zEnd;
+  const unsigned char *zTerm = &pCsr->aInput[pCsr->nInput];
+
+  /* Scan past any delimiter characters before the start of the next token.
+  ** Return SQLITE_DONE early if this takes us all the way to the end of 
+  ** the input.  */
+  while( z<zTerm ){
+    READ_UTF8(z, zTerm, iCode);
+    if( unicodeIsAlnum(p, iCode) ) break;
+    zStart = z;
+  }
+  if( zStart>=zTerm ) return SQLITE_DONE;
+
+  zOut = pCsr->zToken;
+  do {
+    int iOut;
+
+    /* Grow the output buffer if required. */
+    if( (zOut-pCsr->zToken)>=(pCsr->nAlloc-4) ){
+      char *zNew = sqlite3_realloc(pCsr->zToken, pCsr->nAlloc+64);
+      if( !zNew ) return SQLITE_NOMEM;
+      zOut = &zNew[zOut - pCsr->zToken];
+      pCsr->zToken = zNew;
+      pCsr->nAlloc += 64;
+    }
+
+    /* Write the folded case of the last character read to the output */
+    zEnd = z;
+    iOut = sqlite3FtsUnicodeFold(iCode, p->bRemoveDiacritic);
+    if( iOut ){
+      WRITE_UTF8(zOut, iOut);
+    }
+
+    /* If the cursor is not at EOF, read the next character */
+    if( z>=zTerm ) break;
+    READ_UTF8(z, zTerm, iCode);
+  }while( unicodeIsAlnum(p, iCode) 
+       || sqlite3FtsUnicodeIsdiacritic(iCode)
+  );
+
+  /* Set the output variables and return. */
+  pCsr->iOff = (z - pCsr->aInput);
+  *paToken = pCsr->zToken;
+  *pnToken = zOut - pCsr->zToken;
+  *piStart = (zStart - pCsr->aInput);
+  *piEnd = (zEnd - pCsr->aInput);
+  *piPos = pCsr->iToken++;
+  return SQLITE_OK;
+}
+
+/*
+** Set *ppModule to a pointer to the sqlite3_tokenizer_module 
+** structure for the unicode tokenizer.
+*/
+void sqlite3Fts3UnicodeTokenizer(sqlite3_tokenizer_module const **ppModule){
+  static const sqlite3_tokenizer_module module = {
+    0,
+    unicodeCreate,
+    unicodeDestroy,
+    unicodeOpen,
+    unicodeClose,
+    unicodeNext,
+    0,
+  };
+  *ppModule = &module;
+}
+
+#endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3) */
+#endif /* ifndef SQLITE_ENABLE_FTS4_UNICODE61 */
diff --git a/src/libtracker-fts/fts3_unicode2.c b/src/libtracker-fts/fts3_unicode2.c
new file mode 100644
index 000000000..3c2456902
--- /dev/null
+++ b/src/libtracker-fts/fts3_unicode2.c
@@ -0,0 +1,366 @@
+/*
+** 2012 May 25
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+*/
+
+/*
+** DO NOT EDIT THIS MACHINE GENERATED FILE.
+*/
+
+#if defined(SQLITE_ENABLE_FTS4_UNICODE61)
+#if defined(SQLITE_ENABLE_FTS3) || defined(SQLITE_ENABLE_FTS4)
+
+#include <assert.h>
+
+/*
+** Return true if the argument corresponds to a unicode codepoint
+** classified as either a letter or a number. Otherwise false.
+**
+** The results are undefined if the value passed to this function
+** is less than zero.
+*/
+int sqlite3FtsUnicodeIsalnum(int c){
+  /* Each unsigned integer in the following array corresponds to a contiguous
+  ** range of unicode codepoints that are not either letters or numbers (i.e.
+  ** codepoints for which this function should return 0).
+  **
+  ** The most significant 22 bits in each 32-bit value contain the first 
+  ** codepoint in the range. The least significant 10 bits are used to store
+  ** the size of the range (always at least 1). In other words, the value 
+  ** ((C<<22) + N) represents a range of N codepoints starting with codepoint 
+  ** C. It is not possible to represent a range larger than 1023 codepoints 
+  ** using this format.
+  */
+  const static unsigned int aEntry[] = {
+    0x00000030, 0x0000E807, 0x00016C06, 0x0001EC2F, 0x0002AC07,
+    0x0002D001, 0x0002D803, 0x0002EC01, 0x0002FC01, 0x00035C01,
+    0x0003DC01, 0x000B0804, 0x000B480E, 0x000B9407, 0x000BB401,
+    0x000BBC81, 0x000DD401, 0x000DF801, 0x000E1002, 0x000E1C01,
+    0x000FD801, 0x00120808, 0x00156806, 0x00162402, 0x00163C01,
+    0x00164437, 0x0017CC02, 0x00180005, 0x00181816, 0x00187802,
+    0x00192C15, 0x0019A804, 0x0019C001, 0x001B5001, 0x001B580F,
+    0x001B9C07, 0x001BF402, 0x001C000E, 0x001C3C01, 0x001C4401,
+    0x001CC01B, 0x001E980B, 0x001FAC09, 0x001FD804, 0x00205804,
+    0x00206C09, 0x00209403, 0x0020A405, 0x0020C00F, 0x00216403,
+    0x00217801, 0x0023901B, 0x00240004, 0x0024E803, 0x0024F812,
+    0x00254407, 0x00258804, 0x0025C001, 0x00260403, 0x0026F001,
+    0x0026F807, 0x00271C02, 0x00272C03, 0x00275C01, 0x00278802,
+    0x0027C802, 0x0027E802, 0x00280403, 0x0028F001, 0x0028F805,
+    0x00291C02, 0x00292C03, 0x00294401, 0x0029C002, 0x0029D401,
+    0x002A0403, 0x002AF001, 0x002AF808, 0x002B1C03, 0x002B2C03,
+    0x002B8802, 0x002BC002, 0x002C0403, 0x002CF001, 0x002CF807,
+    0x002D1C02, 0x002D2C03, 0x002D5802, 0x002D8802, 0x002DC001,
+    0x002E0801, 0x002EF805, 0x002F1803, 0x002F2804, 0x002F5C01,
+    0x002FCC08, 0x00300403, 0x0030F807, 0x00311803, 0x00312804,
+    0x00315402, 0x00318802, 0x0031FC01, 0x00320802, 0x0032F001,
+    0x0032F807, 0x00331803, 0x00332804, 0x00335402, 0x00338802,
+    0x00340802, 0x0034F807, 0x00351803, 0x00352804, 0x00355C01,
+    0x00358802, 0x0035E401, 0x00360802, 0x00372801, 0x00373C06,
+    0x00375801, 0x00376008, 0x0037C803, 0x0038C401, 0x0038D007,
+    0x0038FC01, 0x00391C09, 0x00396802, 0x003AC401, 0x003AD006,
+    0x003AEC02, 0x003B2006, 0x003C041F, 0x003CD00C, 0x003DC417,
+    0x003E340B, 0x003E6424, 0x003EF80F, 0x003F380D, 0x0040AC14,
+    0x00412806, 0x00415804, 0x00417803, 0x00418803, 0x00419C07,
+    0x0041C404, 0x0042080C, 0x00423C01, 0x00426806, 0x0043EC01,
+    0x004D740C, 0x004E400A, 0x00500001, 0x0059B402, 0x005A0001,
+    0x005A6C02, 0x005BAC03, 0x005C4803, 0x005CC805, 0x005D4802,
+    0x005DC802, 0x005ED023, 0x005F6004, 0x005F7401, 0x0060000F,
+    0x0062A401, 0x0064800C, 0x0064C00C, 0x00650001, 0x00651002,
+    0x0066C011, 0x00672002, 0x00677822, 0x00685C05, 0x00687802,
+    0x0069540A, 0x0069801D, 0x0069FC01, 0x006A8007, 0x006AA006,
+    0x006C0005, 0x006CD011, 0x006D6823, 0x006E0003, 0x006E840D,
+    0x006F980E, 0x006FF004, 0x00709014, 0x0070EC05, 0x0071F802,
+    0x00730008, 0x00734019, 0x0073B401, 0x0073C803, 0x00770027,
+    0x0077F004, 0x007EF401, 0x007EFC03, 0x007F3403, 0x007F7403,
+    0x007FB403, 0x007FF402, 0x00800065, 0x0081A806, 0x0081E805,
+    0x00822805, 0x0082801A, 0x00834021, 0x00840002, 0x00840C04,
+    0x00842002, 0x00845001, 0x00845803, 0x00847806, 0x00849401,
+    0x00849C01, 0x0084A401, 0x0084B801, 0x0084E802, 0x00850005,
+    0x00852804, 0x00853C01, 0x00864264, 0x00900027, 0x0091000B,
+    0x0092704E, 0x00940200, 0x009C0475, 0x009E53B9, 0x00AD400A,
+    0x00B39406, 0x00B3BC03, 0x00B3E404, 0x00B3F802, 0x00B5C001,
+    0x00B5FC01, 0x00B7804F, 0x00B8C00C, 0x00BA001A, 0x00BA6C59,
+    0x00BC00D6, 0x00BFC00C, 0x00C00005, 0x00C02019, 0x00C0A807,
+    0x00C0D802, 0x00C0F403, 0x00C26404, 0x00C28001, 0x00C3EC01,
+    0x00C64002, 0x00C6580A, 0x00C70024, 0x00C8001F, 0x00C8A81E,
+    0x00C94001, 0x00C98020, 0x00CA2827, 0x00CB003F, 0x00CC0100,
+    0x01370040, 0x02924037, 0x0293F802, 0x02983403, 0x0299BC10,
+    0x029A7C01, 0x029BC008, 0x029C0017, 0x029C8002, 0x029E2402,
+    0x02A00801, 0x02A01801, 0x02A02C01, 0x02A08C09, 0x02A0D804,
+    0x02A1D004, 0x02A20002, 0x02A2D011, 0x02A33802, 0x02A38012,
+    0x02A3E003, 0x02A4980A, 0x02A51C0D, 0x02A57C01, 0x02A60004,
+    0x02A6CC1B, 0x02A77802, 0x02A8A40E, 0x02A90C01, 0x02A93002,
+    0x02A97004, 0x02A9DC03, 0x02A9EC01, 0x02AAC001, 0x02AAC803,
+    0x02AADC02, 0x02AAF802, 0x02AB0401, 0x02AB7802, 0x02ABAC07,
+    0x02ABD402, 0x02AF8C0B, 0x03600001, 0x036DFC02, 0x036FFC02,
+    0x037FFC02, 0x03E3FC01, 0x03EC7801, 0x03ECA401, 0x03EEC810,
+    0x03F4F802, 0x03F7F002, 0x03F8001A, 0x03F88007, 0x03F8C023,
+    0x03F95013, 0x03F9A004, 0x03FBFC01, 0x03FC040F, 0x03FC6807,
+    0x03FCEC06, 0x03FD6C0B, 0x03FF8007, 0x03FFA007, 0x03FFE405,
+    0x04040003, 0x0404DC09, 0x0405E411, 0x0406400C, 0x0407402E,
+    0x040E7C01, 0x040F4001, 0x04215C01, 0x04247C01, 0x0424FC01,
+    0x04280403, 0x04281402, 0x04283004, 0x0428E003, 0x0428FC01,
+    0x04294009, 0x0429FC01, 0x042CE407, 0x04400003, 0x0440E016,
+    0x04420003, 0x0442C012, 0x04440003, 0x04449C0E, 0x04450004,
+    0x04460003, 0x0446CC0E, 0x04471404, 0x045AAC0D, 0x0491C004,
+    0x05BD442E, 0x05BE3C04, 0x074000F6, 0x07440027, 0x0744A4B5,
+    0x07480046, 0x074C0057, 0x075B0401, 0x075B6C01, 0x075BEC01,
+    0x075C5401, 0x075CD401, 0x075D3C01, 0x075DBC01, 0x075E2401,
+    0x075EA401, 0x075F0C01, 0x07BBC002, 0x07C0002C, 0x07C0C064,
+    0x07C2800F, 0x07C2C40E, 0x07C3040F, 0x07C3440F, 0x07C4401F,
+    0x07C4C03C, 0x07C5C02B, 0x07C7981D, 0x07C8402B, 0x07C90009,
+    0x07C94002, 0x07CC0021, 0x07CCC006, 0x07CCDC46, 0x07CE0014,
+    0x07CE8025, 0x07CF1805, 0x07CF8011, 0x07D0003F, 0x07D10001,
+    0x07D108B6, 0x07D3E404, 0x07D4003E, 0x07D50004, 0x07D54018,
+    0x07D7EC46, 0x07D9140B, 0x07DA0046, 0x07DC0074, 0x38000401,
+    0x38008060, 0x380400F0, 0x3C000001, 0x3FFFF401, 0x40000001,
+    0x43FFF401,
+  };
+  static const unsigned int aAscii[4] = {
+    0xFFFFFFFF, 0xFC00FFFF, 0xF8000001, 0xF8000001,
+  };
+
+  if( c<128 ){
+    return ( (aAscii[c >> 5] & (1 << (c & 0x001F)))==0 );
+  }else if( c<(1<<22) ){
+    unsigned int key = (((unsigned int)c)<<10) | 0x000003FF;
+    int iRes;
+    int iHi = sizeof(aEntry)/sizeof(aEntry[0]) - 1;
+    int iLo = 0;
+    while( iHi>=iLo ){
+      int iTest = (iHi + iLo) / 2;
+      if( key >= aEntry[iTest] ){
+        iRes = iTest;
+        iLo = iTest+1;
+      }else{
+        iHi = iTest-1;
+      }
+    }
+    assert( aEntry[0]<key );
+    assert( key>=aEntry[iRes] );
+    return (((unsigned int)c) >= ((aEntry[iRes]>>10) + (aEntry[iRes]&0x3FF)));
+  }
+  return 1;
+}
+
+
+/*
+** If the argument is a codepoint corresponding to a lowercase letter
+** in the ASCII range with a diacritic added, return the codepoint
+** of the ASCII letter only. For example, if passed 235 - "LATIN
+** SMALL LETTER E WITH DIAERESIS" - return 65 ("LATIN SMALL LETTER
+** E"). The resuls of passing a codepoint that corresponds to an
+** uppercase letter are undefined.
+*/
+static int remove_diacritic(int c){
+  unsigned short aDia[] = {
+        0,  1797,  1848,  1859,  1891,  1928,  1940,  1995, 
+     2024,  2040,  2060,  2110,  2168,  2206,  2264,  2286, 
+     2344,  2383,  2472,  2488,  2516,  2596,  2668,  2732, 
+     2782,  2842,  2894,  2954,  2984,  3000,  3028,  3336, 
+     3456,  3696,  3712,  3728,  3744,  3896,  3912,  3928, 
+     3968,  4008,  4040,  4106,  4138,  4170,  4202,  4234, 
+     4266,  4296,  4312,  4344,  4408,  4424,  4472,  4504, 
+     6148,  6198,  6264,  6280,  6360,  6429,  6505,  6529, 
+    61448, 61468, 61534, 61592, 61642, 61688, 61704, 61726, 
+    61784, 61800, 61836, 61880, 61914, 61948, 61998, 62122, 
+    62154, 62200, 62218, 62302, 62364, 62442, 62478, 62536, 
+    62554, 62584, 62604, 62640, 62648, 62656, 62664, 62730, 
+    62924, 63050, 63082, 63274, 63390, 
+  };
+  char aChar[] = {
+    '\0', 'a',  'c',  'e',  'i',  'n',  'o',  'u',  'y',  'y',  'a',  'c',  
+    'd',  'e',  'e',  'g',  'h',  'i',  'j',  'k',  'l',  'n',  'o',  'r',  
+    's',  't',  'u',  'u',  'w',  'y',  'z',  'o',  'u',  'a',  'i',  'o',  
+    'u',  'g',  'k',  'o',  'j',  'g',  'n',  'a',  'e',  'i',  'o',  'r',  
+    'u',  's',  't',  'h',  'a',  'e',  'o',  'y',  '\0', '\0', '\0', '\0', 
+    '\0', '\0', '\0', '\0', 'a',  'b',  'd',  'd',  'e',  'f',  'g',  'h',  
+    'h',  'i',  'k',  'l',  'l',  'm',  'n',  'p',  'r',  'r',  's',  't',  
+    'u',  'v',  'w',  'w',  'x',  'y',  'z',  'h',  't',  'w',  'y',  'a',  
+    'e',  'i',  'o',  'u',  'y',  
+  };
+
+  unsigned int key = (((unsigned int)c)<<3) | 0x00000007;
+  int iRes = 0;
+  int iHi = sizeof(aDia)/sizeof(aDia[0]) - 1;
+  int iLo = 0;
+  while( iHi>=iLo ){
+    int iTest = (iHi + iLo) / 2;
+    if( key >= aDia[iTest] ){
+      iRes = iTest;
+      iLo = iTest+1;
+    }else{
+      iHi = iTest-1;
+    }
+  }
+  assert( key>=aDia[iRes] );
+  return ((c > (aDia[iRes]>>3) + (aDia[iRes]&0x07)) ? c : (int)aChar[iRes]);
+};
+
+
+/*
+** Return true if the argument interpreted as a unicode codepoint
+** is a diacritical modifier character.
+*/
+int sqlite3FtsUnicodeIsdiacritic(int c){
+  unsigned int mask0 = 0x08029FDF;
+  unsigned int mask1 = 0x000361F8;
+  if( c<768 || c>817 ) return 0;
+  return (c < 768+32) ?
+      (mask0 & (1 << (c-768))) :
+      (mask1 & (1 << (c-768-32)));
+}
+
+
+/*
+** Interpret the argument as a unicode codepoint. If the codepoint
+** is an upper case character that has a lower case equivalent,
+** return the codepoint corresponding to the lower case version.
+** Otherwise, return a copy of the argument.
+**
+** The results are undefined if the value passed to this function
+** is less than zero.
+*/
+int sqlite3FtsUnicodeFold(int c, int bRemoveDiacritic){
+  /* Each entry in the following array defines a rule for folding a range
+  ** of codepoints to lower case. The rule applies to a range of nRange
+  ** codepoints starting at codepoint iCode.
+  **
+  ** If the least significant bit in flags is clear, then the rule applies
+  ** to all nRange codepoints (i.e. all nRange codepoints are upper case and
+  ** need to be folded). Or, if it is set, then the rule only applies to
+  ** every second codepoint in the range, starting with codepoint C.
+  **
+  ** The 7 most significant bits in flags are an index into the aiOff[]
+  ** array. If a specific codepoint C does require folding, then its lower
+  ** case equivalent is ((C + aiOff[flags>>1]) & 0xFFFF).
+  **
+  ** The contents of this array are generated by parsing the CaseFolding.txt
+  ** file distributed as part of the "Unicode Character Database". See
+  ** http://www.unicode.org for details.
+  */
+  static const struct TableEntry {
+    unsigned short iCode;
+    unsigned char flags;
+    unsigned char nRange;
+  } aEntry[] = {
+    {65, 14, 26},          {181, 64, 1},          {192, 14, 23},
+    {216, 14, 7},          {256, 1, 48},          {306, 1, 6},
+    {313, 1, 16},          {330, 1, 46},          {376, 116, 1},
+    {377, 1, 6},           {383, 104, 1},         {385, 50, 1},
+    {386, 1, 4},           {390, 44, 1},          {391, 0, 1},
+    {393, 42, 2},          {395, 0, 1},           {398, 32, 1},
+    {399, 38, 1},          {400, 40, 1},          {401, 0, 1},
+    {403, 42, 1},          {404, 46, 1},          {406, 52, 1},
+    {407, 48, 1},          {408, 0, 1},           {412, 52, 1},
+    {413, 54, 1},          {415, 56, 1},          {416, 1, 6},
+    {422, 60, 1},          {423, 0, 1},           {425, 60, 1},
+    {428, 0, 1},           {430, 60, 1},          {431, 0, 1},
+    {433, 58, 2},          {435, 1, 4},           {439, 62, 1},
+    {440, 0, 1},           {444, 0, 1},           {452, 2, 1},
+    {453, 0, 1},           {455, 2, 1},           {456, 0, 1},
+    {458, 2, 1},           {459, 1, 18},          {478, 1, 18},
+    {497, 2, 1},           {498, 1, 4},           {502, 122, 1},
+    {503, 134, 1},         {504, 1, 40},          {544, 110, 1},
+    {546, 1, 18},          {570, 70, 1},          {571, 0, 1},
+    {573, 108, 1},         {574, 68, 1},          {577, 0, 1},
+    {579, 106, 1},         {580, 28, 1},          {581, 30, 1},
+    {582, 1, 10},          {837, 36, 1},          {880, 1, 4},
+    {886, 0, 1},           {902, 18, 1},          {904, 16, 3},
+    {908, 26, 1},          {910, 24, 2},          {913, 14, 17},
+    {931, 14, 9},          {962, 0, 1},           {975, 4, 1},
+    {976, 140, 1},         {977, 142, 1},         {981, 146, 1},
+    {982, 144, 1},         {984, 1, 24},          {1008, 136, 1},
+    {1009, 138, 1},        {1012, 130, 1},        {1013, 128, 1},
+    {1015, 0, 1},          {1017, 152, 1},        {1018, 0, 1},
+    {1021, 110, 3},        {1024, 34, 16},        {1040, 14, 32},
+    {1120, 1, 34},         {1162, 1, 54},         {1216, 6, 1},
+    {1217, 1, 14},         {1232, 1, 88},         {1329, 22, 38},
+    {4256, 66, 38},        {4295, 66, 1},         {4301, 66, 1},
+    {7680, 1, 150},        {7835, 132, 1},        {7838, 96, 1},
+    {7840, 1, 96},         {7944, 150, 8},        {7960, 150, 6},
+    {7976, 150, 8},        {7992, 150, 8},        {8008, 150, 6},
+    {8025, 151, 8},        {8040, 150, 8},        {8072, 150, 8},
+    {8088, 150, 8},        {8104, 150, 8},        {8120, 150, 2},
+    {8122, 126, 2},        {8124, 148, 1},        {8126, 100, 1},
+    {8136, 124, 4},        {8140, 148, 1},        {8152, 150, 2},
+    {8154, 120, 2},        {8168, 150, 2},        {8170, 118, 2},
+    {8172, 152, 1},        {8184, 112, 2},        {8186, 114, 2},
+    {8188, 148, 1},        {8486, 98, 1},         {8490, 92, 1},
+    {8491, 94, 1},         {8498, 12, 1},         {8544, 8, 16},
+    {8579, 0, 1},          {9398, 10, 26},        {11264, 22, 47},
+    {11360, 0, 1},         {11362, 88, 1},        {11363, 102, 1},
+    {11364, 90, 1},        {11367, 1, 6},         {11373, 84, 1},
+    {11374, 86, 1},        {11375, 80, 1},        {11376, 82, 1},
+    {11378, 0, 1},         {11381, 0, 1},         {11390, 78, 2},
+    {11392, 1, 100},       {11499, 1, 4},         {11506, 0, 1},
+    {42560, 1, 46},        {42624, 1, 24},        {42786, 1, 14},
+    {42802, 1, 62},        {42873, 1, 4},         {42877, 76, 1},
+    {42878, 1, 10},        {42891, 0, 1},         {42893, 74, 1},
+    {42896, 1, 4},         {42912, 1, 10},        {42922, 72, 1},
+    {65313, 14, 26},       
+  };
+  static const unsigned short aiOff[] = {
+   1,     2,     8,     15,    16,    26,    28,    32,    
+   37,    38,    40,    48,    63,    64,    69,    71,    
+   79,    80,    116,   202,   203,   205,   206,   207,   
+   209,   210,   211,   213,   214,   217,   218,   219,   
+   775,   7264,  10792, 10795, 23228, 23256, 30204, 54721, 
+   54753, 54754, 54756, 54787, 54793, 54809, 57153, 57274, 
+   57921, 58019, 58363, 61722, 65268, 65341, 65373, 65406, 
+   65408, 65410, 65415, 65424, 65436, 65439, 65450, 65462, 
+   65472, 65476, 65478, 65480, 65482, 65488, 65506, 65511, 
+   65514, 65521, 65527, 65528, 65529, 
+  };
+
+  int ret = c;
+
+  assert( c>=0 );
+  assert( sizeof(unsigned short)==2 && sizeof(unsigned char)==1 );
+
+  if( c<128 ){
+    if( c>='A' && c<='Z' ) ret = c + ('a' - 'A');
+  }else if( c<65536 ){
+    int iHi = sizeof(aEntry)/sizeof(aEntry[0]) - 1;
+    int iLo = 0;
+    int iRes = -1;
+
+    while( iHi>=iLo ){
+      int iTest = (iHi + iLo) / 2;
+      int cmp = (c - aEntry[iTest].iCode);
+      if( cmp>=0 ){
+        iRes = iTest;
+        iLo = iTest+1;
+      }else{
+        iHi = iTest-1;
+      }
+    }
+    assert( iRes<0 || c>=aEntry[iRes].iCode );
+
+    if( iRes>=0 ){
+      const struct TableEntry *p = &aEntry[iRes];
+      if( c<(p->iCode + p->nRange) && 0==(0x01 & p->flags & (p->iCode ^ c)) ){
+        ret = (c + (aiOff[p->flags>>1])) & 0x0000FFFF;
+        assert( ret>0 );
+      }
+    }
+
+    if( bRemoveDiacritic ) ret = remove_diacritic(ret);
+  }
+  
+  else if( c>=66560 && c<66600 ){
+    ret = c + 40;
+  }
+
+  return ret;
+}
+#endif /* defined(SQLITE_ENABLE_FTS3) || defined(SQLITE_ENABLE_FTS4) */
+#endif /* !defined(SQLITE_ENABLE_FTS4_UNICODE61) */
diff --git a/src/libtracker-fts/fts3_write.c b/src/libtracker-fts/fts3_write.c
index 36f2249e1..bda7fbbe1 100644
--- a/src/libtracker-fts/fts3_write.c
+++ b/src/libtracker-fts/fts3_write.c
@@ -24,6 +24,9 @@
 #include <assert.h>
 #include <stdlib.h>
 
+
+#define FTS_MAX_APPENDABLE_HEIGHT 16
+
 /*
 ** When full-text index nodes are loaded from disk, the buffer that they
 ** are loaded into has the following number of bytes of padding at the end 
@@ -63,6 +66,29 @@ int test_fts3_node_chunk_threshold = (4*1024)*4;
 # define FTS3_NODE_CHUNK_THRESHOLD (FTS3_NODE_CHUNKSIZE*4)
 #endif
 
+/*
+** The two values that may be meaningfully bound to the :1 parameter in
+** statements SQL_REPLACE_STAT and SQL_SELECT_STAT.
+*/
+#define FTS_STAT_DOCTOTAL      0
+#define FTS_STAT_INCRMERGEHINT 1
+#define FTS_STAT_AUTOINCRMERGE 2
+
+/*
+** If FTS_LOG_MERGES is defined, call sqlite3_log() to report each automatic
+** and incremental merge operation that takes place. This is used for 
+** debugging FTS only, it should not usually be turned on in production
+** systems.
+*/
+#ifdef FTS3_LOG_MERGES
+static void fts3LogMerge(int nMerge, sqlite3_int64 iAbsLevel){
+  sqlite3_log(SQLITE_OK, "%d-way merge from level %d", nMerge, (int)iAbsLevel);
+}
+#else
+#define fts3LogMerge(x, y)
+#endif
+
+
 typedef struct PendingList PendingList;
 typedef struct SegmentNode SegmentNode;
 typedef struct SegmentWriter SegmentWriter;
@@ -110,6 +136,8 @@ struct Fts3DeferredToken {
 */
 struct Fts3SegReader {
   int iIdx;                       /* Index within level, or 0x7FFFFFFF for PT */
+  u8 bLookup;                     /* True for a lookup only */
+  u8 rootOnly;                    /* True for a root-only reader */
 
   sqlite3_int64 iStartBlock;      /* Rowid of first leaf block to traverse */
   sqlite3_int64 iLeafEndBlock;    /* Rowid of final leaf block to traverse */
@@ -143,7 +171,7 @@ struct Fts3SegReader {
 };
 
 #define fts3SegReaderIsPending(p) ((p)->ppNextElem!=0)
-#define fts3SegReaderIsRootOnly(p) ((p)->aNode==(char *)&(p)[1])
+#define fts3SegReaderIsRootOnly(p) ((p)->rootOnly!=0)
 
 /*
 ** An instance of this structure is used to create a segment b-tree in the
@@ -223,13 +251,22 @@ struct SegmentNode {
 #define SQL_DELETE_DOCSIZE            19
 #define SQL_REPLACE_DOCSIZE           20
 #define SQL_SELECT_DOCSIZE            21
-#define SQL_SELECT_DOCTOTAL           22
-#define SQL_REPLACE_DOCTOTAL          23
+#define SQL_SELECT_STAT               22
+#define SQL_REPLACE_STAT              23
 
 #define SQL_SELECT_ALL_PREFIX_LEVEL   24
 #define SQL_DELETE_ALL_TERMS_SEGDIR   25
-
 #define SQL_DELETE_SEGDIR_RANGE       26
+#define SQL_SELECT_ALL_LANGID         27
+#define SQL_FIND_MERGE_LEVEL          28
+#define SQL_MAX_LEAF_NODE_ESTIMATE    29
+#define SQL_DELETE_SEGDIR_ENTRY       30
+#define SQL_SHIFT_SEGDIR_ENTRY        31
+#define SQL_SELECT_SEGDIR             32
+#define SQL_CHOMP_SEGDIR              33
+#define SQL_SEGMENT_IS_APPENDABLE     34
+#define SQL_SELECT_INDEXES            35
+#define SQL_SELECT_MXLEVEL            36
 
 /*
 ** This function is used to obtain an SQLite prepared statement handle
@@ -256,11 +293,11 @@ static int fts3SqlStmt(
 /* 4  */  "DELETE FROM %Q.'%q_segdir'",
 /* 5  */  "DELETE FROM %Q.'%q_docsize'",
 /* 6  */  "DELETE FROM %Q.'%q_stat'",
-/* 7  */  "SELECT %s FROM %Q.'%q_content' AS x WHERE rowid=?",
+/* 7  */  "SELECT %s WHERE rowid=?",
 /* 8  */  "SELECT (SELECT max(idx) FROM %Q.'%q_segdir' WHERE level = ?) + 1",
-/* 9  */  "INSERT INTO %Q.'%q_segments'(blockid, block) VALUES(?, ?)",
+/* 9  */  "REPLACE INTO %Q.'%q_segments'(blockid, block) VALUES(?, ?)",
 /* 10 */  "SELECT coalesce((SELECT max(blockid) FROM %Q.'%q_segments') + 1, 1)",
-/* 11 */  "INSERT INTO %Q.'%q_segdir' VALUES(?,?,?,?,?,?)",
+/* 11 */  "REPLACE INTO %Q.'%q_segdir' VALUES(?,?,?,?,?,?)",
 
           /* Return segments in order from oldest to newest.*/ 
 /* 12 */  "SELECT idx, start_block, leaves_end_block, end_block, root "
@@ -278,13 +315,61 @@ static int fts3SqlStmt(
 /* 19 */  "DELETE FROM %Q.'%q_docsize' WHERE docid = ?",
 /* 20 */  "REPLACE INTO %Q.'%q_docsize' VALUES(?,?)",
 /* 21 */  "SELECT size FROM %Q.'%q_docsize' WHERE docid=?",
-/* 22 */  "SELECT value FROM %Q.'%q_stat' WHERE id=0",
-/* 23 */  "REPLACE INTO %Q.'%q_stat' VALUES(0,?)",
+/* 22 */  "SELECT value FROM %Q.'%q_stat' WHERE id=?",
+/* 23 */  "REPLACE INTO %Q.'%q_stat' VALUES(?,?)",
 /* 24 */  "",
 /* 25 */  "",
 
 /* 26 */ "DELETE FROM %Q.'%q_segdir' WHERE level BETWEEN ? AND ?",
-
+/* 27 */ "SELECT DISTINCT level / (1024 * ?) FROM %Q.'%q_segdir'",
+
+/* This statement is used to determine which level to read the input from
+** when performing an incremental merge. It returns the absolute level number
+** of the oldest level in the db that contains at least ? segments. Or,
+** if no level in the FTS index contains more than ? segments, the statement
+** returns zero rows.  */
+/* 28 */ "SELECT level FROM %Q.'%q_segdir' GROUP BY level HAVING count(*)>=?"
+         "  ORDER BY (level %% 1024) ASC LIMIT 1",
+
+/* Estimate the upper limit on the number of leaf nodes in a new segment
+** created by merging the oldest :2 segments from absolute level :1. See 
+** function sqlite3Fts3Incrmerge() for details.  */
+/* 29 */ "SELECT 2 * total(1 + leaves_end_block - start_block) "
+         "  FROM %Q.'%q_segdir' WHERE level = ? AND idx < ?",
+
+/* SQL_DELETE_SEGDIR_ENTRY
+**   Delete the %_segdir entry on absolute level :1 with index :2.  */
+/* 30 */ "DELETE FROM %Q.'%q_segdir' WHERE level = ? AND idx = ?",
+
+/* SQL_SHIFT_SEGDIR_ENTRY
+**   Modify the idx value for the segment with idx=:3 on absolute level :2
+**   to :1.  */
+/* 31 */ "UPDATE %Q.'%q_segdir' SET idx = ? WHERE level=? AND idx=?",
+
+/* SQL_SELECT_SEGDIR
+**   Read a single entry from the %_segdir table. The entry from absolute 
+**   level :1 with index value :2.  */
+/* 32 */  "SELECT idx, start_block, leaves_end_block, end_block, root "
+            "FROM %Q.'%q_segdir' WHERE level = ? AND idx = ?",
+
+/* SQL_CHOMP_SEGDIR
+**   Update the start_block (:1) and root (:2) fields of the %_segdir
+**   entry located on absolute level :3 with index :4.  */
+/* 33 */  "UPDATE %Q.'%q_segdir' SET start_block = ?, root = ?"
+            "WHERE level = ? AND idx = ?",
+
+/* SQL_SEGMENT_IS_APPENDABLE
+**   Return a single row if the segment with end_block=? is appendable. Or
+**   no rows otherwise.  */
+/* 34 */  "SELECT 1 FROM %Q.'%q_segments' WHERE blockid=? AND block IS NULL",
+
+/* SQL_SELECT_INDEXES
+**   Return the list of valid segment indexes for absolute level ?  */
+/* 35 */  "SELECT idx FROM %Q.'%q_segdir' WHERE level=? ORDER BY 1 ASC",
+
+/* SQL_SELECT_MXLEVEL
+**   Return the largest relative level in the FTS index or indexes.  */
+/* 36 */  "SELECT max( level %% 1024 ) FROM %Q.'%q_segdir'"
   };
   int rc = SQLITE_OK;
   sqlite3_stmt *pStmt;
@@ -298,7 +383,7 @@ static int fts3SqlStmt(
     if( eStmt==SQL_CONTENT_INSERT ){
       zSql = sqlite3_mprintf(azSql[eStmt], p->zDb, p->zName, p->zWriteExprlist);
     }else if( eStmt==SQL_SELECT_CONTENT_BY_ROWID ){
-      zSql = sqlite3_mprintf(azSql[eStmt], p->zReadExprlist, p->zDb, p->zName);
+      zSql = sqlite3_mprintf(azSql[eStmt], p->zReadExprlist);
     }else{
       zSql = sqlite3_mprintf(azSql[eStmt], p->zDb, p->zName);
     }
@@ -322,26 +407,22 @@ static int fts3SqlStmt(
   return rc;
 }
 
+
 static int fts3SelectDocsize(
   Fts3Table *pTab,                /* FTS3 table handle */
-  int eStmt,                      /* Either SQL_SELECT_DOCSIZE or DOCTOTAL */
   sqlite3_int64 iDocid,           /* Docid to bind for SQL_SELECT_DOCSIZE */
   sqlite3_stmt **ppStmt           /* OUT: Statement handle */
 ){
   sqlite3_stmt *pStmt = 0;        /* Statement requested from fts3SqlStmt() */
   int rc;                         /* Return code */
 
-  assert( eStmt==SQL_SELECT_DOCSIZE || eStmt==SQL_SELECT_DOCTOTAL );
-
-  rc = fts3SqlStmt(pTab, eStmt, &pStmt, 0);
+  rc = fts3SqlStmt(pTab, SQL_SELECT_DOCSIZE, &pStmt, 0);
   if( rc==SQLITE_OK ){
-    if( eStmt==SQL_SELECT_DOCSIZE ){
-      sqlite3_bind_int64(pStmt, 1, iDocid);
-    }
+    sqlite3_bind_int64(pStmt, 1, iDocid);
     rc = sqlite3_step(pStmt);
     if( rc!=SQLITE_ROW || sqlite3_column_type(pStmt, 0)!=SQLITE_BLOB ){
       rc = sqlite3_reset(pStmt);
-      if( rc==SQLITE_OK ) rc = SQLITE_CORRUPT_VTAB;
+      if( rc==SQLITE_OK ) rc = FTS_CORRUPT_VTAB;
       pStmt = 0;
     }else{
       rc = SQLITE_OK;
@@ -356,7 +437,21 @@ int sqlite3Fts3SelectDoctotal(
   Fts3Table *pTab,                /* Fts3 table handle */
   sqlite3_stmt **ppStmt           /* OUT: Statement handle */
 ){
-  return fts3SelectDocsize(pTab, SQL_SELECT_DOCTOTAL, 0, ppStmt);
+  sqlite3_stmt *pStmt = 0;
+  int rc;
+  rc = fts3SqlStmt(pTab, SQL_SELECT_STAT, &pStmt, 0);
+  if( rc==SQLITE_OK ){
+    sqlite3_bind_int(pStmt, 1, FTS_STAT_DOCTOTAL);
+    if( sqlite3_step(pStmt)!=SQLITE_ROW
+     || sqlite3_column_type(pStmt, 0)!=SQLITE_BLOB
+    ){
+      rc = sqlite3_reset(pStmt);
+      if( rc==SQLITE_OK ) rc = FTS_CORRUPT_VTAB;
+      pStmt = 0;
+    }
+  }
+  *ppStmt = pStmt;
+  return rc;
 }
 
 int sqlite3Fts3SelectDocsize(
@@ -364,7 +459,7 @@ int sqlite3Fts3SelectDocsize(
   sqlite3_int64 iDocid,           /* Docid to read size data for */
   sqlite3_stmt **ppStmt           /* OUT: Statement handle */
 ){
-  return fts3SelectDocsize(pTab, SQL_SELECT_DOCSIZE, iDocid, ppStmt);
+  return fts3SelectDocsize(pTab, iDocid, ppStmt);
 }
 
 /*
@@ -409,21 +504,66 @@ static void fts3SqlExec(
 ** not what users expect when they get SQLITE_LOCKED_SHAREDCACHE. It can
 ** still happen if the user reads data directly from the %_segments or
 ** %_segdir tables instead of going through FTS3 though.
+**
+** This reasoning does not apply to a content=xxx table.
 */
 int sqlite3Fts3ReadLock(Fts3Table *p){
   int rc;                         /* Return code */
   sqlite3_stmt *pStmt;            /* Statement used to obtain lock */
 
-  rc = fts3SqlStmt(p, SQL_SELECT_CONTENT_BY_ROWID, &pStmt, 0);
-  if( rc==SQLITE_OK ){
-    sqlite3_bind_null(pStmt, 1);
-    sqlite3_step(pStmt);
-    rc = sqlite3_reset(pStmt);
+  if( p->zContentTbl==0 ){
+    rc = fts3SqlStmt(p, SQL_SELECT_CONTENT_BY_ROWID, &pStmt, 0);
+    if( rc==SQLITE_OK ){
+      sqlite3_bind_null(pStmt, 1);
+      sqlite3_step(pStmt);
+      rc = sqlite3_reset(pStmt);
+    }
+  }else{
+    rc = SQLITE_OK;
   }
+
   return rc;
 }
 
 /*
+** FTS maintains a separate indexes for each language-id (a 32-bit integer).
+** Within each language id, a separate index is maintained to store the
+** document terms, and each configured prefix size (configured the FTS 
+** "prefix=" option). And each index consists of multiple levels ("relative
+** levels").
+**
+** All three of these values (the language id, the specific index and the
+** level within the index) are encoded in 64-bit integer values stored
+** in the %_segdir table on disk. This function is used to convert three
+** separate component values into the single 64-bit integer value that
+** can be used to query the %_segdir table.
+**
+** Specifically, each language-id/index combination is allocated 1024 
+** 64-bit integer level values ("absolute levels"). The main terms index
+** for language-id 0 is allocate values 0-1023. The first prefix index
+** (if any) for language-id 0 is allocated values 1024-2047. And so on.
+** Language 1 indexes are allocated immediately following language 0.
+**
+** So, for a system with nPrefix prefix indexes configured, the block of
+** absolute levels that corresponds to language-id iLangid and index 
+** iIndex starts at absolute level ((iLangid * (nPrefix+1) + iIndex) * 1024).
+*/
+static sqlite3_int64 getAbsoluteLevel(
+  Fts3Table *p,                   /* FTS3 table handle */
+  int iLangid,                    /* Language id */
+  int iIndex,                     /* Index in p->aIndex[] */
+  int iLevel                      /* Level of segments */
+){
+  sqlite3_int64 iBase;            /* First absolute level for iLangid/iIndex */
+  assert( iLangid>=0 );
+  assert( p->nIndex>0 );
+  assert( iIndex>=0 && iIndex<p->nIndex );
+
+  iBase = ((sqlite3_int64)iLangid * p->nIndex + iIndex) * FTS3_SEGDIR_MAXLEVEL;
+  return iBase + iLevel;
+}
+
+/*
 ** Set *ppStmt to a statement handle that may be used to iterate through
 ** all rows in the %_segdir table, from oldest to newest. If successful,
 ** return SQLITE_OK. If an error occurs while preparing the statement, 
@@ -442,8 +582,9 @@ int sqlite3Fts3ReadLock(Fts3Table *p){
 */
 int sqlite3Fts3AllSegdirs(
   Fts3Table *p,                   /* FTS3 table */
+  int iLangid,                    /* Language being queried */
   int iIndex,                     /* Index for p->aIndex[] */
-  int iLevel,                     /* Level to select */
+  int iLevel,                     /* Level to select (relative level) */
   sqlite3_stmt **ppStmt           /* OUT: Compiled statement */
 ){
   int rc;
@@ -457,14 +598,16 @@ int sqlite3Fts3AllSegdirs(
     /* "SELECT * FROM %_segdir WHERE level BETWEEN ? AND ? ORDER BY ..." */
     rc = fts3SqlStmt(p, SQL_SELECT_LEVEL_RANGE, &pStmt, 0);
     if( rc==SQLITE_OK ){ 
-      sqlite3_bind_int(pStmt, 1, iIndex*FTS3_SEGDIR_MAXLEVEL);
-      sqlite3_bind_int(pStmt, 2, (iIndex+1)*FTS3_SEGDIR_MAXLEVEL-1);
+      sqlite3_bind_int64(pStmt, 1, getAbsoluteLevel(p, iLangid, iIndex, 0));
+      sqlite3_bind_int64(pStmt, 2, 
+          getAbsoluteLevel(p, iLangid, iIndex, FTS3_SEGDIR_MAXLEVEL-1)
+      );
     }
   }else{
     /* "SELECT * FROM %_segdir WHERE level = ? ORDER BY ..." */
     rc = fts3SqlStmt(p, SQL_SELECT_LEVEL, &pStmt, 0);
     if( rc==SQLITE_OK ){ 
-      sqlite3_bind_int(pStmt, 1, iLevel+iIndex*FTS3_SEGDIR_MAXLEVEL);
+      sqlite3_bind_int64(pStmt, 1, getAbsoluteLevel(p, iLangid, iIndex,iLevel));
     }
   }
   *ppStmt = pStmt;
@@ -630,18 +773,19 @@ static int fts3PendingTermsAddOne(
 */
 static int fts3PendingTermsAdd(
   Fts3Table *p,                   /* Table into which text will be inserted */
+  int iLangid,                    /* Language id to use */
   const char *zText,              /* Text of document to be inserted */
   int iCol,                       /* Column into which text is being inserted */
-  u32 *pnWord                     /* OUT: Number of tokens inserted */
+  u32 *pnWord                     /* IN/OUT: Incr. by number tokens inserted */
 ){
   int rc;
-  int iStart;
-  int iEnd;
-  int iPos;
+  int iStart = 0;
+  int iEnd = 0;
+  int iPos = 0;
   int nWord = 0;
 
   char const *zToken;
-  int nToken;
+  int nToken = 0;
 
   sqlite3_tokenizer *pTokenizer = p->pTokenizer;
   sqlite3_tokenizer_module const *pModule = pTokenizer->pModule;
@@ -659,11 +803,10 @@ static int fts3PendingTermsAdd(
     return SQLITE_OK;
   }
 
-  rc = pModule->xOpen(pTokenizer, zText, -1, &pCsr);
+  rc = sqlite3Fts3OpenTokenizer(pTokenizer, iLangid, zText, -1, &pCsr);
   if( rc!=SQLITE_OK ){
     return rc;
   }
-  pCsr->pTokenizer = pTokenizer;
 
   xNext = pModule->xNext;
   while( SQLITE_OK==rc
@@ -697,7 +840,7 @@ static int fts3PendingTermsAdd(
   }
 
   pModule->xClose(pCsr);
-  *pnWord = nWord;
+  *pnWord += nWord;
   return (rc==SQLITE_DONE ? SQLITE_OK : rc);
 }
 
@@ -706,18 +849,28 @@ static int fts3PendingTermsAdd(
 ** fts3PendingTermsAdd() are to add term/position-list pairs for the
 ** contents of the document with docid iDocid.
 */
-static int fts3PendingTermsDocid(Fts3Table *p, sqlite_int64 iDocid){
+static int fts3PendingTermsDocid(
+  Fts3Table *p,                   /* Full-text table handle */
+  int iLangid,                    /* Language id of row being written */
+  sqlite_int64 iDocid             /* Docid of row being written */
+){
+  assert( iLangid>=0 );
+
   /* TODO(shess) Explore whether partially flushing the buffer on
   ** forced-flush would provide better performance.  I suspect that if
   ** we ordered the doclists by size and flushed the largest until the
   ** buffer was half empty, that would let the less frequent terms
   ** generate longer doclists.
   */
-  if( iDocid<=p->iPrevDocid || p->nPendingData>p->nMaxPendingData ){
+  if( iDocid<=p->iPrevDocid 
+   || p->iPrevLangid!=iLangid
+   || p->nPendingData>p->nMaxPendingData 
+  ){
     int rc = sqlite3Fts3PendingTermsFlush(p);
     if( rc!=SQLITE_OK ) return rc;
   }
   p->iPrevDocid = iDocid;
+  p->iPrevLangid = iLangid;
   return SQLITE_OK;
 }
 
@@ -746,11 +899,16 @@ void sqlite3Fts3PendingTermsClear(Fts3Table *p){
 ** Argument apVal is the same as the similarly named argument passed to
 ** fts3InsertData(). Parameter iDocid is the docid of the new row.
 */
-static int fts3InsertTerms(Fts3Table *p, sqlite3_value **apVal, u32 *aSz){
+static int fts3InsertTerms(
+  Fts3Table *p, 
+  int iLangid, 
+  sqlite3_value **apVal, 
+  u32 *aSz
+){
   int i;                          /* Iterator variable */
   for(i=2; i<p->nColumn+2; i++){
     const char *zText = (const char *)sqlite3_value_text(apVal[i]);
-    int rc = fts3PendingTermsAdd(p, zText, i-2, &aSz[i-2]);
+    int rc = fts3PendingTermsAdd(p, iLangid, zText, i-2, &aSz[i-2]);
     if( rc!=SQLITE_OK ){
       return rc;
     }
@@ -771,6 +929,7 @@ static int fts3InsertTerms(Fts3Table *p, sqlite3_value **apVal, u32 *aSz){
 **   apVal[p->nColumn+1]     Right-most user-defined column
 **   apVal[p->nColumn+2]     Hidden column with same name as table
 **   apVal[p->nColumn+3]     Hidden "docid" column (alias for rowid)
+**   apVal[p->nColumn+4]     Hidden languageid column
 */
 static int fts3InsertData(
   Fts3Table *p,                   /* Full-text table */
@@ -780,6 +939,18 @@ static int fts3InsertData(
   int rc;                         /* Return code */
   sqlite3_stmt *pContentInsert;   /* INSERT INTO %_content VALUES(...) */
 
+  if( p->zContentTbl ){
+    sqlite3_value *pRowid = apVal[p->nColumn+3];
+    if( sqlite3_value_type(pRowid)==SQLITE_NULL ){
+      pRowid = apVal[1];
+    }
+    if( sqlite3_value_type(pRowid)!=SQLITE_INTEGER ){
+      return SQLITE_CONSTRAINT;
+    }
+    *piDocid = sqlite3_value_int64(pRowid);
+    return SQLITE_OK;
+  }
+
   /* Locate the statement handle used to insert data into the %_content
   ** table. The SQL for this statement is:
   **
@@ -789,9 +960,13 @@ static int fts3InsertData(
   ** defined columns in the FTS3 table, plus one for the docid field.
   */
   rc = fts3SqlStmt(p, SQL_CONTENT_INSERT, &pContentInsert, &apVal[1]);
-  if( rc!=SQLITE_OK ){
-    return rc;
+  if( rc==SQLITE_OK && p->zLanguageid ){
+    rc = sqlite3_bind_int(
+        pContentInsert, p->nColumn+2, 
+        sqlite3_value_int(apVal[p->nColumn+4])
+    );
   }
+  if( rc!=SQLITE_OK ) return rc;
 
   /* There is a quirk here. The users INSERT statement may have specified
   ** a value for the "rowid" field, for the "docid" field, or for both.
@@ -830,14 +1005,16 @@ static int fts3InsertData(
 ** Remove all data from the FTS3 table. Clear the hash table containing
 ** pending terms.
 */
-static int fts3DeleteAll(Fts3Table *p){
+static int fts3DeleteAll(Fts3Table *p, int bContent){
   int rc = SQLITE_OK;             /* Return code */
 
   /* Discard the contents of the pending-terms hash table. */
   sqlite3Fts3PendingTermsClear(p);
 
-  /* Delete everything from the %_content, %_segments and %_segdir tables. */
-  fts3SqlExec(&rc, p, SQL_DELETE_ALL_CONTENT, 0);
+  /* Delete everything from the shadow tables. Except, leave %_content as
+  ** is if bContent is false.  */
+  assert( p->zContentTbl==0 || bContent==0 );
+  if( bContent ) fts3SqlExec(&rc, p, SQL_DELETE_ALL_CONTENT, 0);
   fts3SqlExec(&rc, p, SQL_DELETE_ALL_SEGMENTS, 0);
   fts3SqlExec(&rc, p, SQL_DELETE_ALL_SEGDIR, 0);
   if( p->bHasDocsize ){
@@ -850,6 +1027,15 @@ static int fts3DeleteAll(Fts3Table *p){
 }
 
 /*
+**
+*/
+static int langidFromSelect(Fts3Table *p, sqlite3_stmt *pSelect){
+  int iLangid = 0;
+  if( p->zLanguageid ) iLangid = sqlite3_column_int(pSelect, p->nColumn+1);
+  return iLangid;
+}
+
+/*
 ** The first element in the apVal[] array is assumed to contain the docid
 ** (an integer) of a row about to be deleted. Remove all terms from the
 ** full-text index.
@@ -858,26 +1044,31 @@ static void fts3DeleteTerms(
   int *pRC,               /* Result code */
   Fts3Table *p,           /* The FTS table to delete from */
   sqlite3_value *pRowid,  /* The docid to be deleted */
-  u32 *aSz                /* Sizes of deleted document written here */
+  u32 *aSz,               /* Sizes of deleted document written here */
+  int *pbFound            /* OUT: Set to true if row really does exist */
 ){
   int rc;
   sqlite3_stmt *pSelect;
 
+  assert( *pbFound==0 );
   if( *pRC ) return;
   rc = fts3SqlStmt(p, SQL_SELECT_CONTENT_BY_ROWID, &pSelect, &pRowid);
   if( rc==SQLITE_OK ){
     if( SQLITE_ROW==sqlite3_step(pSelect) ){
       int i;
-      for(i=1; i<=p->nColumn; i++){
+      int iLangid = langidFromSelect(p, pSelect);
+      rc = fts3PendingTermsDocid(p, iLangid, sqlite3_column_int64(pSelect, 0));
+      for(i=1; rc==SQLITE_OK && i<=p->nColumn; i++){
         const char *zText = (const char *)sqlite3_column_text(pSelect, i);
-        rc = fts3PendingTermsAdd(p, zText, -1, &aSz[i-1]);
-        if( rc!=SQLITE_OK ){
-          sqlite3_reset(pSelect);
-          *pRC = rc;
-          return;
-        }
+        rc = fts3PendingTermsAdd(p, iLangid, zText, -1, &aSz[i-1]);
         aSz[p->nColumn] += sqlite3_column_bytes(pSelect, i);
       }
+      if( rc!=SQLITE_OK ){
+        sqlite3_reset(pSelect);
+        *pRC = rc;
+        return;
+      }
+      *pbFound = 1;
     }
     rc = sqlite3_reset(pSelect);
   }else{
@@ -890,7 +1081,7 @@ static void fts3DeleteTerms(
 ** Forward declaration to account for the circular dependency between
 ** functions fts3SegmentMerge() and fts3AllocateSegdirIdx().
 */
-static int fts3SegmentMerge(Fts3Table *, int, int);
+static int fts3SegmentMerge(Fts3Table *, int, int, int);
 
 /* 
 ** This function allocates a new level iLevel index in the segdir table.
@@ -909,6 +1100,7 @@ static int fts3SegmentMerge(Fts3Table *, int, int);
 */
 static int fts3AllocateSegdirIdx(
   Fts3Table *p, 
+  int iLangid,                    /* Language id */
   int iIndex,                     /* Index for p->aIndex */
   int iLevel, 
   int *piIdx
@@ -917,10 +1109,15 @@ static int fts3AllocateSegdirIdx(
   sqlite3_stmt *pNextIdx;         /* Query for next idx at level iLevel */
   int iNext = 0;                  /* Result of query pNextIdx */
 
+  assert( iLangid>=0 );
+  assert( p->nIndex>=1 );
+
   /* Set variable iNext to the next available segdir index at level iLevel. */
   rc = fts3SqlStmt(p, SQL_NEXT_SEGMENT_INDEX, &pNextIdx, 0);
   if( rc==SQLITE_OK ){
-    sqlite3_bind_int(pNextIdx, 1, iIndex*FTS3_SEGDIR_MAXLEVEL + iLevel);
+    sqlite3_bind_int64(
+        pNextIdx, 1, getAbsoluteLevel(p, iLangid, iIndex, iLevel)
+    );
     if( SQLITE_ROW==sqlite3_step(pNextIdx) ){
       iNext = sqlite3_column_int(pNextIdx, 0);
     }
@@ -934,7 +1131,8 @@ static int fts3AllocateSegdirIdx(
     ** if iNext is less than FTS3_MERGE_COUNT, allocate index iNext.
     */
     if( iNext>=FTS3_MERGE_COUNT ){
-      rc = fts3SegmentMerge(p, iIndex, iLevel);
+      fts3LogMerge(16, getAbsoluteLevel(p, iLangid, iIndex, iLevel));
+      rc = fts3SegmentMerge(p, iLangid, iIndex, iLevel);
       *piIdx = 0;
     }else{
       *piIdx = iNext;
@@ -981,7 +1179,7 @@ int sqlite3Fts3ReadBlock(
   int rc;                         /* Return code */
 
   /* pnBlob must be non-NULL. paBlob may be NULL or non-NULL. */
-  assert( pnBlob);
+  assert( pnBlob );
 
   if( p->pSegments ){
     rc = sqlite3_blob_reopen(p->pSegments, iBlockid);
@@ -1068,6 +1266,18 @@ static int fts3SegReaderRequire(Fts3SegReader *pReader, char *pFrom, int nByte){
 }
 
 /*
+** Set an Fts3SegReader cursor to point at EOF.
+*/
+static void fts3SegReaderSetEof(Fts3SegReader *pSeg){
+  if( !fts3SegReaderIsRootOnly(pSeg) ){
+    sqlite3_free(pSeg->aNode);
+    sqlite3_blob_close(pSeg->pBlob);
+    pSeg->pBlob = 0;
+  }
+  pSeg->aNode = 0;
+}
+
+/*
 ** Move the iterator passed as the first argument to the next term in the
 ** segment. If successful, SQLITE_OK is returned. If there is no next term,
 ** SQLITE_DONE. Otherwise, an SQLite error code.
@@ -1106,12 +1316,7 @@ static int fts3SegReaderNext(
       return SQLITE_OK;
     }
 
-    if( !fts3SegReaderIsRootOnly(pReader) ){
-      sqlite3_free(pReader->aNode);
-      sqlite3_blob_close(pReader->pBlob);
-      pReader->pBlob = 0;
-    }
-    pReader->aNode = 0;
+    fts3SegReaderSetEof(pReader);
 
     /* If iCurrentBlock>=iLeafEndBlock, this is an EOF condition. All leaf 
     ** blocks have already been traversed.  */
@@ -1145,7 +1350,7 @@ static int fts3SegReaderNext(
   if( nPrefix<0 || nSuffix<=0 
    || &pNext[nSuffix]>&pReader->aNode[pReader->nNode] 
   ){
-    return SQLITE_CORRUPT_VTAB;
+    return FTS_CORRUPT_VTAB;
   }
 
   if( nPrefix+nSuffix>pReader->nTermAlloc ){
@@ -1175,7 +1380,7 @@ static int fts3SegReaderNext(
   if( &pReader->aDoclist[pReader->nDoclist]>&pReader->aNode[pReader->nNode] 
    || (pReader->nPopulate==0 && pReader->aDoclist[pReader->nDoclist-1])
   ){
-    return SQLITE_CORRUPT_VTAB;
+    return FTS_CORRUPT_VTAB;
   }
   return SQLITE_OK;
 }
@@ -1315,7 +1520,7 @@ int sqlite3Fts3MsrOvfl(
   int rc = SQLITE_OK;
   int pgsz = p->nPgsz;
 
-  assert( p->bHasStat );
+  assert( p->bFts4 );
   assert( pgsz>0 );
 
   for(ii=0; rc==SQLITE_OK && ii<pMsr->nSegment; ii++){
@@ -1358,6 +1563,7 @@ void sqlite3Fts3SegReaderFree(Fts3SegReader *pReader){
 */
 int sqlite3Fts3SegReaderNew(
   int iAge,                       /* Segment "age". */
+  int bLookup,                    /* True for a lookup only */
   sqlite3_int64 iStartLeaf,       /* First leaf to traverse */
   sqlite3_int64 iEndLeaf,         /* Final leaf to traverse */
   sqlite3_int64 iEndBlock,        /* Final block of segment */
@@ -1365,7 +1571,6 @@ int sqlite3Fts3SegReaderNew(
   int nRoot,                      /* Size of buffer containing root node */
   Fts3SegReader **ppReader        /* OUT: Allocated Fts3SegReader */
 ){
-  int rc = SQLITE_OK;             /* Return code */
   Fts3SegReader *pReader;         /* Newly allocated SegReader object */
   int nExtra = 0;                 /* Bytes to allocate segment root node */
 
@@ -1380,6 +1585,7 @@ int sqlite3Fts3SegReaderNew(
   }
   memset(pReader, 0, sizeof(Fts3SegReader));
   pReader->iIdx = iAge;
+  pReader->bLookup = bLookup!=0;
   pReader->iStartBlock = iStartLeaf;
   pReader->iLeafEndBlock = iEndLeaf;
   pReader->iEndBlock = iEndBlock;
@@ -1387,19 +1593,15 @@ int sqlite3Fts3SegReaderNew(
   if( nExtra ){
     /* The entire segment is stored in the root node. */
     pReader->aNode = (char *)&pReader[1];
+    pReader->rootOnly = 1;
     pReader->nNode = nRoot;
     memcpy(pReader->aNode, zRoot, nRoot);
     memset(&pReader->aNode[nRoot], 0, FTS3_NODE_PADDING);
   }else{
     pReader->iCurrentBlock = iStartLeaf-1;
   }
-
-  if( rc==SQLITE_OK ){
-    *ppReader = pReader;
-  }else{
-    sqlite3Fts3SegReaderFree(pReader);
-  }
-  return rc;
+  *ppReader = pReader;
+  return SQLITE_OK;
 }
 
 /*
@@ -1449,6 +1651,7 @@ int sqlite3Fts3SegReaderPending(
   Fts3SegReader **ppReader        /* OUT: SegReader for pending-terms */
 ){
   Fts3SegReader *pReader = 0;     /* Fts3SegReader object to return */
+  Fts3HashElem *pE;               /* Iterator variable */
   Fts3HashElem **aElem = 0;       /* Array of term hash entries to scan */
   int nElem = 0;                  /* Size of array at aElem */
   int rc = SQLITE_OK;             /* Return Code */
@@ -1457,7 +1660,6 @@ int sqlite3Fts3SegReaderPending(
   pHash = &p->aIndex[iIndex].hPending;
   if( bPrefix ){
     int nAlloc = 0;               /* Size of allocated array at aElem */
-    Fts3HashElem *pE = 0;         /* Iterator variable */
 
     for(pE=fts3HashFirst(pHash); pE; pE=fts3HashNext(pE)){
       char *zKey = (char *)fts3HashKey(pE);
@@ -1491,8 +1693,13 @@ int sqlite3Fts3SegReaderPending(
 
   }else{
     /* The query is a simple term lookup that matches at most one term in
-    ** the index. All that is required is a straight hash-lookup. */
-    Fts3HashElem *pE = fts3HashFindElem(pHash, zTerm, nTerm);
+    ** the index. All that is required is a straight hash-lookup. 
+    **
+    ** Because the stack address of pE may be accessed via the aElem pointer
+    ** below, the "Fts3HashElem *pE" must be declared so that it is valid
+    ** within this entire function, not just this "else{...}" block.
+    */
+    pE = fts3HashFindElem(pHash, zTerm, nTerm);
     if( pE ){
       aElem = &pE;
       nElem = 1;
@@ -1672,12 +1879,33 @@ static int fts3WriteSegment(
   return rc;
 }
 
+/*
+** Find the largest relative level number in the table. If successful, set
+** *pnMax to this value and return SQLITE_OK. Otherwise, if an error occurs,
+** set *pnMax to zero and return an SQLite error code.
+*/
+int sqlite3Fts3MaxLevel(Fts3Table *p, int *pnMax){
+  int rc;
+  int mxLevel = 0;
+  sqlite3_stmt *pStmt = 0;
+
+  rc = fts3SqlStmt(p, SQL_SELECT_MXLEVEL, &pStmt, 0);
+  if( rc==SQLITE_OK ){
+    if( SQLITE_ROW==sqlite3_step(pStmt) ){
+      mxLevel = sqlite3_column_int(pStmt, 0);
+    }
+    rc = sqlite3_reset(pStmt);
+  }
+  *pnMax = mxLevel;
+  return rc;
+}
+
 /* 
 ** Insert a record into the %_segdir table.
 */
 static int fts3WriteSegdir(
   Fts3Table *p,                   /* Virtual table handle */
-  int iLevel,                     /* Value for "level" field */
+  sqlite3_int64 iLevel,           /* Value for "level" field (absolute level) */
   int iIdx,                       /* Value for "idx" field */
   sqlite3_int64 iStartBlock,      /* Value for "start_block" field */
   sqlite3_int64 iLeafEndBlock,    /* Value for "leaves_end_block" field */
@@ -1688,7 +1916,7 @@ static int fts3WriteSegdir(
   sqlite3_stmt *pStmt;
   int rc = fts3SqlStmt(p, SQL_INSERT_SEGDIR, &pStmt, 0);
   if( rc==SQLITE_OK ){
-    sqlite3_bind_int(pStmt, 1, iLevel);
+    sqlite3_bind_int64(pStmt, 1, iLevel);
     sqlite3_bind_int(pStmt, 2, iIdx);
     sqlite3_bind_int64(pStmt, 3, iStartBlock);
     sqlite3_bind_int64(pStmt, 4, iLeafEndBlock);
@@ -1988,6 +2216,7 @@ static int fts3SegWriterAdd(
     /* The current leaf node is full. Write it out to the database. */
     rc = fts3WriteSegment(p, pWriter->iFree++, pWriter->aData, nData);
     if( rc!=SQLITE_OK ) return rc;
+    p->nLeafAdd++;
 
     /* Add the current term to the interior node tree. The term added to
     ** the interior tree must:
@@ -2071,7 +2300,7 @@ static int fts3SegWriterAdd(
 static int fts3SegWriterFlush(
   Fts3Table *p,                   /* Virtual table handle */
   SegmentWriter *pWriter,         /* SegmentWriter to flush to the db */
-  int iLevel,                     /* Value for 'level' column of %_segdir */
+  sqlite3_int64 iLevel,           /* Value for 'level' column of %_segdir */
   int iIdx                        /* Value for 'idx' column of %_segdir */
 ){
   int rc;                         /* Return code */
@@ -2096,6 +2325,7 @@ static int fts3SegWriterFlush(
     rc = fts3WriteSegdir(
         p, iLevel, iIdx, 0, 0, 0, pWriter->aData, pWriter->nData);
   }
+  p->nLeafAdd++;
   return rc;
 }
 
@@ -2125,12 +2355,18 @@ static void fts3SegWriterFree(SegmentWriter *pWriter){
 static int fts3IsEmpty(Fts3Table *p, sqlite3_value *pRowid, int *pisEmpty){
   sqlite3_stmt *pStmt;
   int rc;
-  rc = fts3SqlStmt(p, SQL_IS_EMPTY, &pStmt, &pRowid);
-  if( rc==SQLITE_OK ){
-    if( SQLITE_ROW==sqlite3_step(pStmt) ){
-      *pisEmpty = sqlite3_column_int(pStmt, 0);
+  if( p->zContentTbl ){
+    /* If using the content=xxx option, assume the table is never empty */
+    *pisEmpty = 0;
+    rc = SQLITE_OK;
+  }else{
+    rc = fts3SqlStmt(p, SQL_IS_EMPTY, &pStmt, &pRowid);
+    if( rc==SQLITE_OK ){
+      if( SQLITE_ROW==sqlite3_step(pStmt) ){
+        *pisEmpty = sqlite3_column_int(pStmt, 0);
+      }
+      rc = sqlite3_reset(pStmt);
     }
-    rc = sqlite3_reset(pStmt);
   }
   return rc;
 }
@@ -2143,7 +2379,12 @@ static int fts3IsEmpty(Fts3Table *p, sqlite3_value *pRowid, int *pisEmpty){
 **
 ** Return SQLITE_OK if successful, or an SQLite error code if not.
 */
-static int fts3SegmentMaxLevel(Fts3Table *p, int iIndex, int *pnMax){
+static int fts3SegmentMaxLevel(
+  Fts3Table *p, 
+  int iLangid,
+  int iIndex, 
+  sqlite3_int64 *pnMax
+){
   sqlite3_stmt *pStmt;
   int rc;
   assert( iIndex>=0 && iIndex<p->nIndex );
@@ -2156,15 +2397,40 @@ static int fts3SegmentMaxLevel(Fts3Table *p, int iIndex, int *pnMax){
   */
   rc = fts3SqlStmt(p, SQL_SELECT_SEGDIR_MAX_LEVEL, &pStmt, 0);
   if( rc!=SQLITE_OK ) return rc;
-  sqlite3_bind_int(pStmt, 1, iIndex*FTS3_SEGDIR_MAXLEVEL);
-  sqlite3_bind_int(pStmt, 2, (iIndex+1)*FTS3_SEGDIR_MAXLEVEL - 1);
+  sqlite3_bind_int64(pStmt, 1, getAbsoluteLevel(p, iLangid, iIndex, 0));
+  sqlite3_bind_int64(pStmt, 2, 
+      getAbsoluteLevel(p, iLangid, iIndex, FTS3_SEGDIR_MAXLEVEL-1)
+  );
   if( SQLITE_ROW==sqlite3_step(pStmt) ){
-    *pnMax = sqlite3_column_int(pStmt, 0);
+    *pnMax = sqlite3_column_int64(pStmt, 0);
   }
   return sqlite3_reset(pStmt);
 }
 
 /*
+** Delete all entries in the %_segments table associated with the segment
+** opened with seg-reader pSeg. This function does not affect the contents
+** of the %_segdir table.
+*/
+static int fts3DeleteSegment(
+  Fts3Table *p,                   /* FTS table handle */
+  Fts3SegReader *pSeg             /* Segment to delete */
+){
+  int rc = SQLITE_OK;             /* Return code */
+  if( pSeg->iStartBlock ){
+    sqlite3_stmt *pDelete;        /* SQL statement to delete rows */
+    rc = fts3SqlStmt(p, SQL_DELETE_SEGMENTS_RANGE, &pDelete, 0);
+    if( rc==SQLITE_OK ){
+      sqlite3_bind_int64(pDelete, 1, pSeg->iStartBlock);
+      sqlite3_bind_int64(pDelete, 2, pSeg->iEndBlock);
+      sqlite3_step(pDelete);
+      rc = sqlite3_reset(pDelete);
+    }
+  }
+  return rc;
+}
+
+/*
 ** This function is used after merging multiple segments into a single large
 ** segment to delete the old, now redundant, segment b-trees. Specifically,
 ** it:
@@ -2180,24 +2446,18 @@ static int fts3SegmentMaxLevel(Fts3Table *p, int iIndex, int *pnMax){
 */
 static int fts3DeleteSegdir(
   Fts3Table *p,                   /* Virtual table handle */
+  int iLangid,                    /* Language id */
   int iIndex,                     /* Index for p->aIndex */
   int iLevel,                     /* Level of %_segdir entries to delete */
   Fts3SegReader **apSegment,      /* Array of SegReader objects */
   int nReader                     /* Size of array apSegment */
 ){
-  int rc;                         /* Return Code */
+  int rc = SQLITE_OK;             /* Return Code */
   int i;                          /* Iterator variable */
-  sqlite3_stmt *pDelete;          /* SQL statement to delete rows */
+  sqlite3_stmt *pDelete = 0;      /* SQL statement to delete rows */
 
-  rc = fts3SqlStmt(p, SQL_DELETE_SEGMENTS_RANGE, &pDelete, 0);
   for(i=0; rc==SQLITE_OK && i<nReader; i++){
-    Fts3SegReader *pSegment = apSegment[i];
-    if( pSegment->iStartBlock ){
-      sqlite3_bind_int64(pDelete, 1, pSegment->iStartBlock);
-      sqlite3_bind_int64(pDelete, 2, pSegment->iEndBlock);
-      sqlite3_step(pDelete);
-      rc = sqlite3_reset(pDelete);
-    }
+    rc = fts3DeleteSegment(p, apSegment[i]);
   }
   if( rc!=SQLITE_OK ){
     return rc;
@@ -2207,13 +2467,17 @@ static int fts3DeleteSegdir(
   if( iLevel==FTS3_SEGCURSOR_ALL ){
     rc = fts3SqlStmt(p, SQL_DELETE_SEGDIR_RANGE, &pDelete, 0);
     if( rc==SQLITE_OK ){
-      sqlite3_bind_int(pDelete, 1, iIndex*FTS3_SEGDIR_MAXLEVEL);
-      sqlite3_bind_int(pDelete, 2, (iIndex+1) * FTS3_SEGDIR_MAXLEVEL - 1);
+      sqlite3_bind_int64(pDelete, 1, getAbsoluteLevel(p, iLangid, iIndex, 0));
+      sqlite3_bind_int64(pDelete, 2, 
+          getAbsoluteLevel(p, iLangid, iIndex, FTS3_SEGDIR_MAXLEVEL-1)
+      );
     }
   }else{
     rc = fts3SqlStmt(p, SQL_DELETE_SEGDIR_LEVEL, &pDelete, 0);
     if( rc==SQLITE_OK ){
-      sqlite3_bind_int(pDelete, 1, iIndex*FTS3_SEGDIR_MAXLEVEL + iLevel);
+      sqlite3_bind_int64(
+          pDelete, 1, getAbsoluteLevel(p, iLangid, iIndex, iLevel)
+      );
     }
   }
 
@@ -2376,11 +2640,16 @@ static int fts3SegReaderStart(
   ** b-tree leaf nodes contain more than one term.
   */
   for(i=0; pCsr->bRestart==0 && i<pCsr->nSegment; i++){
+    int res = 0;
     Fts3SegReader *pSeg = pCsr->apSegment[i];
     do {
       int rc = fts3SegReaderNext(p, pSeg, 0);
       if( rc!=SQLITE_OK ) return rc;
-    }while( zTerm && fts3SegReaderTermCmp(pSeg, zTerm, nTerm)<0 );
+    }while( zTerm && (res = fts3SegReaderTermCmp(pSeg, zTerm, nTerm))<0 );
+
+    if( pSeg->bLookup && res!=0 ){
+      fts3SegReaderSetEof(pSeg);
+    }
   }
   fts3SegReaderSort(pCsr->apSegment, nSeg, nSeg, fts3SegReaderCmp);
 
@@ -2482,6 +2751,7 @@ int sqlite3Fts3SegReaderStep(
   int isColFilter =    (pCsr->pFilter->flags & FTS3_SEGMENT_COLUMN_FILTER);
   int isPrefix =       (pCsr->pFilter->flags & FTS3_SEGMENT_PREFIX);
   int isScan =         (pCsr->pFilter->flags & FTS3_SEGMENT_SCAN);
+  int isFirst =        (pCsr->pFilter->flags & FTS3_SEGMENT_FIRST);
 
   Fts3SegReader **apSegment = pCsr->apSegment;
   int nSegment = pCsr->nSegment;
@@ -2500,7 +2770,12 @@ int sqlite3Fts3SegReaderStep(
     ** forward. Then sort the list in order of current term again.  
     */
     for(i=0; i<pCsr->nAdvance; i++){
-      rc = fts3SegReaderNext(p, apSegment[i], 0);
+      Fts3SegReader *pSeg = apSegment[i];
+      if( pSeg->bLookup ){
+        fts3SegReaderSetEof(pSeg);
+      }else{
+        rc = fts3SegReaderNext(p, pSeg, 0);
+      }
       if( rc!=SQLITE_OK ) return rc;
     }
     fts3SegReaderSort(apSegment, nSegment, pCsr->nAdvance, fts3SegReaderCmp);
@@ -2541,6 +2816,7 @@ int sqlite3Fts3SegReaderStep(
     assert( isIgnoreEmpty || (isRequirePos && !isColFilter) );
     if( nMerge==1 
      && !isIgnoreEmpty 
+     && !isFirst 
      && (p->bDescIdx==0 || fts3SegReaderIsPending(apSegment[0])==0)
     ){
       pCsr->nDoclist = apSegment[0]->nDoclist;
@@ -2606,12 +2882,24 @@ int sqlite3Fts3SegReaderStep(
             }
             pCsr->aBuffer = aNew;
           }
-          nDoclist += sqlite3Fts3PutVarint(&pCsr->aBuffer[nDoclist], iDelta);
-          iPrev = iDocid;
-          if( isRequirePos ){
-            memcpy(&pCsr->aBuffer[nDoclist], pList, nList);
-            nDoclist += nList;
-            pCsr->aBuffer[nDoclist++] = '\0';
+
+          if( isFirst ){
+            char *a = &pCsr->aBuffer[nDoclist];
+            int nWrite;
+           
+            nWrite = sqlite3Fts3FirstFilter(iDelta, pList, nList, a);
+            if( nWrite ){
+              iPrev = iDocid;
+              nDoclist += nWrite;
+            }
+          }else{
+            nDoclist += sqlite3Fts3PutVarint(&pCsr->aBuffer[nDoclist], iDelta);
+            iPrev = iDocid;
+            if( isRequirePos ){
+              memcpy(&pCsr->aBuffer[nDoclist], pList, nList);
+              nDoclist += nList;
+              pCsr->aBuffer[nDoclist++] = '\0';
+            }
           }
         }
 
@@ -2658,13 +2946,18 @@ void sqlite3Fts3SegReaderFinish(
 ** Otherwise, if successful, SQLITE_OK is returned. If an error occurs, 
 ** an SQLite error code is returned.
 */
-static int fts3SegmentMerge(Fts3Table *p, int iIndex, int iLevel){
+static int fts3SegmentMerge(
+  Fts3Table *p, 
+  int iLangid,                    /* Language id to merge */
+  int iIndex,                     /* Index in p->aIndex[] to merge */
+  int iLevel                      /* Level to merge */
+){
   int rc;                         /* Return code */
   int iIdx = 0;                   /* Index of new segment */
-  int iNewLevel = 0;              /* Level/index to create new segment at */
+  sqlite3_int64 iNewLevel = 0;    /* Level/index to create new segment at */
   SegmentWriter *pWriter = 0;     /* Used to write the new, merged, segment */
   Fts3SegFilter filter;           /* Segment term filter condition */
-  Fts3MultiSegReader csr;        /* Cursor to iterate through level(s) */
+  Fts3MultiSegReader csr;         /* Cursor to iterate through level(s) */
   int bIgnoreEmpty = 0;           /* True to ignore empty segments */
 
   assert( iLevel==FTS3_SEGCURSOR_ALL
@@ -2674,36 +2967,36 @@ static int fts3SegmentMerge(Fts3Table *p, int iIndex, int iLevel){
   assert( iLevel<FTS3_SEGDIR_MAXLEVEL );
   assert( iIndex>=0 && iIndex<p->nIndex );
 
-  rc = sqlite3Fts3SegReaderCursor(p, iIndex, iLevel, 0, 0, 1, 0, &csr);
+  rc = sqlite3Fts3SegReaderCursor(p, iLangid, iIndex, iLevel, 0, 0, 1, 0, &csr);
   if( rc!=SQLITE_OK || csr.nSegment==0 ) goto finished;
 
   if( iLevel==FTS3_SEGCURSOR_ALL ){
     /* This call is to merge all segments in the database to a single
-    ** segment. The level of the new segment is equal to the the numerically 
+    ** segment. The level of the new segment is equal to the numerically
     ** greatest segment level currently present in the database for this
     ** index. The idx of the new segment is always 0.  */
     if( csr.nSegment==1 ){
       rc = SQLITE_DONE;
       goto finished;
     }
-    rc = fts3SegmentMaxLevel(p, iIndex, &iNewLevel);
+    rc = fts3SegmentMaxLevel(p, iLangid, iIndex, &iNewLevel);
     bIgnoreEmpty = 1;
 
   }else if( iLevel==FTS3_SEGCURSOR_PENDING ){
-    iNewLevel = iIndex * FTS3_SEGDIR_MAXLEVEL; 
-    rc = fts3AllocateSegdirIdx(p, iIndex, 0, &iIdx);
+    iNewLevel = getAbsoluteLevel(p, iLangid, iIndex, 0);
+    rc = fts3AllocateSegdirIdx(p, iLangid, iIndex, 0, &iIdx);
   }else{
     /* This call is to merge all segments at level iLevel. find the next
     ** available segment index at level iLevel+1. The call to
     ** fts3AllocateSegdirIdx() will merge the segments at level iLevel+1 to 
     ** a single iLevel+2 segment if necessary.  */
-    rc = fts3AllocateSegdirIdx(p, iIndex, iLevel+1, &iIdx);
-    iNewLevel = iIndex * FTS3_SEGDIR_MAXLEVEL + iLevel+1;
+    rc = fts3AllocateSegdirIdx(p, iLangid, iIndex, iLevel+1, &iIdx);
+    iNewLevel = getAbsoluteLevel(p, iLangid, iIndex, iLevel+1);
   }
   if( rc!=SQLITE_OK ) goto finished;
   assert( csr.nSegment>0 );
-  assert( iNewLevel>=(iIndex*FTS3_SEGDIR_MAXLEVEL) );
-  assert( iNewLevel<((iIndex+1)*FTS3_SEGDIR_MAXLEVEL) );
+  assert( iNewLevel>=getAbsoluteLevel(p, iLangid, iIndex, 0) );
+  assert( iNewLevel<getAbsoluteLevel(p, iLangid, iIndex,FTS3_SEGDIR_MAXLEVEL) );
 
   memset(&filter, 0, sizeof(Fts3SegFilter));
   filter.flags = FTS3_SEGMENT_REQUIRE_POS;
@@ -2720,7 +3013,9 @@ static int fts3SegmentMerge(Fts3Table *p, int iIndex, int iLevel){
   assert( pWriter );
 
   if( iLevel!=FTS3_SEGCURSOR_PENDING ){
-    rc = fts3DeleteSegdir(p, iIndex, iLevel, csr.apSegment, csr.nSegment);
+    rc = fts3DeleteSegdir(
+        p, iLangid, iIndex, iLevel, csr.apSegment, csr.nSegment
+    );
     if( rc!=SQLITE_OK ) goto finished;
   }
   rc = fts3SegWriterFlush(p, pWriter, iNewLevel, iIdx);
@@ -2738,11 +3033,28 @@ static int fts3SegmentMerge(Fts3Table *p, int iIndex, int iLevel){
 int sqlite3Fts3PendingTermsFlush(Fts3Table *p){
   int rc = SQLITE_OK;
   int i;
+        
   for(i=0; rc==SQLITE_OK && i<p->nIndex; i++){
-    rc = fts3SegmentMerge(p, i, FTS3_SEGCURSOR_PENDING);
+    rc = fts3SegmentMerge(p, p->iPrevLangid, i, FTS3_SEGCURSOR_PENDING);
     if( rc==SQLITE_DONE ) rc = SQLITE_OK;
   }
   sqlite3Fts3PendingTermsClear(p);
+
+  /* Determine the auto-incr-merge setting if unknown.  If enabled,
+  ** estimate the number of leaf blocks of content to be written
+  */
+  if( rc==SQLITE_OK && p->bHasStat
+   && p->bAutoincrmerge==0xff && p->nLeafAdd>0
+  ){
+    sqlite3_stmt *pStmt = 0;
+    rc = fts3SqlStmt(p, SQL_SELECT_STAT, &pStmt, 0);
+    if( rc==SQLITE_OK ){
+      sqlite3_bind_int(pStmt, 1, FTS_STAT_AUTOINCRMERGE);
+      rc = sqlite3_step(pStmt);
+      p->bAutoincrmerge = (rc==SQLITE_ROW && sqlite3_column_int(pStmt, 0));
+      rc = sqlite3_reset(pStmt);
+    }
+  }
   return rc;
 }
 
@@ -2787,9 +3099,9 @@ static void fts3DecodeIntArray(
 ** a blob of varints.
 */
 static void fts3InsertDocsize(
-  int *pRC,         /* Result code */
-  Fts3Table *p,     /* Table into which to insert */
-  u32 *aSz          /* Sizes of each column */
+  int *pRC,                       /* Result code */
+  Fts3Table *p,                   /* Table into which to insert */
+  u32 *aSz                        /* Sizes of each column, in tokens */
 ){
   char *pBlob;             /* The BLOB encoding of the document size */
   int nBlob;               /* Number of bytes in the BLOB */
@@ -2853,12 +3165,13 @@ static void fts3UpdateDocTotals(
     return;
   }
   pBlob = (char*)&a[nStat];
-  rc = fts3SqlStmt(p, SQL_SELECT_DOCTOTAL, &pStmt, 0);
+  rc = fts3SqlStmt(p, SQL_SELECT_STAT, &pStmt, 0);
   if( rc ){
     sqlite3_free(a);
     *pRC = rc;
     return;
   }
+  sqlite3_bind_int(pStmt, 1, FTS_STAT_DOCTOTAL);
   if( sqlite3_step(pStmt)==SQLITE_ROW ){
     fts3DecodeIntArray(nStat, a,
          sqlite3_column_blob(pStmt, 0),
@@ -2866,7 +3179,12 @@ static void fts3UpdateDocTotals(
   }else{
     memset(a, 0, sizeof(u32)*(nStat) );
   }
-  sqlite3_reset(pStmt);
+  rc = sqlite3_reset(pStmt);
+  if( rc!=SQLITE_OK ){
+    sqlite3_free(a);
+    *pRC = rc;
+    return;
+  }
   if( nChng<0 && a[0]<(u32)(-nChng) ){
     a[0] = 0;
   }else{
@@ -2882,29 +3200,47 @@ static void fts3UpdateDocTotals(
     a[i+1] = x;
   }
   fts3EncodeIntArray(nStat, a, pBlob, &nBlob);
-  rc = fts3SqlStmt(p, SQL_REPLACE_DOCTOTAL, &pStmt, 0);
+  rc = fts3SqlStmt(p, SQL_REPLACE_STAT, &pStmt, 0);
   if( rc ){
     sqlite3_free(a);
     *pRC = rc;
     return;
   }
-  sqlite3_bind_blob(pStmt, 1, pBlob, nBlob, SQLITE_STATIC);
+  sqlite3_bind_int(pStmt, 1, FTS_STAT_DOCTOTAL);
+  sqlite3_bind_blob(pStmt, 2, pBlob, nBlob, SQLITE_STATIC);
   sqlite3_step(pStmt);
   *pRC = sqlite3_reset(pStmt);
   sqlite3_free(a);
 }
 
+/*
+** Merge the entire database so that there is one segment for each 
+** iIndex/iLangid combination.
+*/
 static int fts3DoOptimize(Fts3Table *p, int bReturnDone){
-  int i;
   int bSeenDone = 0;
-  int rc = SQLITE_OK;
-  for(i=0; rc==SQLITE_OK && i<p->nIndex; i++){
-    rc = fts3SegmentMerge(p, i, FTS3_SEGCURSOR_ALL);
-    if( rc==SQLITE_DONE ){
-      bSeenDone = 1;
-      rc = SQLITE_OK;
+  int rc;
+  sqlite3_stmt *pAllLangid = 0;
+
+  rc = fts3SqlStmt(p, SQL_SELECT_ALL_LANGID, &pAllLangid, 0);
+  if( rc==SQLITE_OK ){
+    int rc2;
+    sqlite3_bind_int(pAllLangid, 1, p->nIndex);
+    while( sqlite3_step(pAllLangid)==SQLITE_ROW ){
+      int i;
+      int iLangid = sqlite3_column_int(pAllLangid, 0);
+      for(i=0; rc==SQLITE_OK && i<p->nIndex; i++){
+        rc = fts3SegmentMerge(p, iLangid, i, FTS3_SEGCURSOR_ALL);
+        if( rc==SQLITE_DONE ){
+          bSeenDone = 1;
+          rc = SQLITE_OK;
+        }
+      }
     }
+    rc2 = sqlite3_reset(pAllLangid);
+    if( rc==SQLITE_OK ) rc = rc2;
   }
+
   sqlite3Fts3SegmentsClose(p);
   sqlite3Fts3PendingTermsClear(p);
 
@@ -2912,6 +3248,1768 @@ static int fts3DoOptimize(Fts3Table *p, int bReturnDone){
 }
 
 /*
+** This function is called when the user executes the following statement:
+**
+**     INSERT INTO <tbl>(<tbl>) VALUES('rebuild');
+**
+** The entire FTS index is discarded and rebuilt. If the table is one 
+** created using the content=xxx option, then the new index is based on
+** the current contents of the xxx table. Otherwise, it is rebuilt based
+** on the contents of the %_content table.
+*/
+static int fts3DoRebuild(Fts3Table *p){
+  int rc;                         /* Return Code */
+
+  rc = fts3DeleteAll(p, 0);
+  if( rc==SQLITE_OK ){
+    u32 *aSz = 0;
+    u32 *aSzIns = 0;
+    u32 *aSzDel = 0;
+    sqlite3_stmt *pStmt = 0;
+    int nEntry = 0;
+
+    /* Compose and prepare an SQL statement to loop through the content table */
+    char *zSql = sqlite3_mprintf("SELECT %s" , p->zReadExprlist);
+    if( !zSql ){
+      rc = SQLITE_NOMEM;
+    }else{
+      rc = sqlite3_prepare_v2(p->db, zSql, -1, &pStmt, 0);
+      sqlite3_free(zSql);
+    }
+
+    if( rc==SQLITE_OK ){
+      int nByte = sizeof(u32) * (p->nColumn+1)*3;
+      aSz = (u32 *)sqlite3_malloc(nByte);
+      if( aSz==0 ){
+        rc = SQLITE_NOMEM;
+      }else{
+        memset(aSz, 0, nByte);
+        aSzIns = &aSz[p->nColumn+1];
+        aSzDel = &aSzIns[p->nColumn+1];
+      }
+    }
+
+    while( rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pStmt) ){
+      int iCol;
+      int iLangid = langidFromSelect(p, pStmt);
+      rc = fts3PendingTermsDocid(p, iLangid, sqlite3_column_int64(pStmt, 0));
+      memset(aSz, 0, sizeof(aSz[0]) * (p->nColumn+1));
+      for(iCol=0; rc==SQLITE_OK && iCol<p->nColumn; iCol++){
+        const char *z = (const char *) sqlite3_column_text(pStmt, iCol+1);
+        rc = fts3PendingTermsAdd(p, iLangid, z, iCol, &aSz[iCol]);
+        aSz[p->nColumn] += sqlite3_column_bytes(pStmt, iCol+1);
+      }
+      if( p->bHasDocsize ){
+        fts3InsertDocsize(&rc, p, aSz);
+      }
+      if( rc!=SQLITE_OK ){
+        sqlite3_finalize(pStmt);
+        pStmt = 0;
+      }else{
+        nEntry++;
+        for(iCol=0; iCol<=p->nColumn; iCol++){
+          aSzIns[iCol] += aSz[iCol];
+        }
+      }
+    }
+    if( p->bFts4 ){
+      fts3UpdateDocTotals(&rc, p, aSzIns, aSzDel, nEntry);
+    }
+    sqlite3_free(aSz);
+
+    if( pStmt ){
+      int rc2 = sqlite3_finalize(pStmt);
+      if( rc==SQLITE_OK ){
+        rc = rc2;
+      }
+    }
+  }
+
+  return rc;
+}
+
+
+/*
+** This function opens a cursor used to read the input data for an 
+** incremental merge operation. Specifically, it opens a cursor to scan
+** the oldest nSeg segments (idx=0 through idx=(nSeg-1)) in absolute 
+** level iAbsLevel.
+*/
+static int fts3IncrmergeCsr(
+  Fts3Table *p,                   /* FTS3 table handle */
+  sqlite3_int64 iAbsLevel,        /* Absolute level to open */
+  int nSeg,                       /* Number of segments to merge */
+  Fts3MultiSegReader *pCsr        /* Cursor object to populate */
+){
+  int rc;                         /* Return Code */
+  sqlite3_stmt *pStmt = 0;        /* Statement used to read %_segdir entry */  
+  int nByte;                      /* Bytes allocated at pCsr->apSegment[] */
+
+  /* Allocate space for the Fts3MultiSegReader.aCsr[] array */
+  memset(pCsr, 0, sizeof(*pCsr));
+  nByte = sizeof(Fts3SegReader *) * nSeg;
+  pCsr->apSegment = (Fts3SegReader **)sqlite3_malloc(nByte);
+
+  if( pCsr->apSegment==0 ){
+    rc = SQLITE_NOMEM;
+  }else{
+    memset(pCsr->apSegment, 0, nByte);
+    rc = fts3SqlStmt(p, SQL_SELECT_LEVEL, &pStmt, 0);
+  }
+  if( rc==SQLITE_OK ){
+    int i;
+    int rc2;
+    sqlite3_bind_int64(pStmt, 1, iAbsLevel);
+    assert( pCsr->nSegment==0 );
+    for(i=0; rc==SQLITE_OK && sqlite3_step(pStmt)==SQLITE_ROW && i<nSeg; i++){
+      rc = sqlite3Fts3SegReaderNew(i, 0,
+          sqlite3_column_int64(pStmt, 1),        /* segdir.start_block */
+          sqlite3_column_int64(pStmt, 2),        /* segdir.leaves_end_block */
+          sqlite3_column_int64(pStmt, 3),        /* segdir.end_block */
+          sqlite3_column_blob(pStmt, 4),         /* segdir.root */
+          sqlite3_column_bytes(pStmt, 4),        /* segdir.root */
+          &pCsr->apSegment[i]
+      );
+      pCsr->nSegment++;
+    }
+    rc2 = sqlite3_reset(pStmt);
+    if( rc==SQLITE_OK ) rc = rc2;
+  }
+
+  return rc;
+}
+
+typedef struct IncrmergeWriter IncrmergeWriter;
+typedef struct NodeWriter NodeWriter;
+typedef struct Blob Blob;
+typedef struct NodeReader NodeReader;
+
+/*
+** An instance of the following structure is used as a dynamic buffer
+** to build up nodes or other blobs of data in.
+**
+** The function blobGrowBuffer() is used to extend the allocation.
+*/
+struct Blob {
+  char *a;                        /* Pointer to allocation */
+  int n;                          /* Number of valid bytes of data in a[] */
+  int nAlloc;                     /* Allocated size of a[] (nAlloc>=n) */
+};
+
+/*
+** This structure is used to build up buffers containing segment b-tree 
+** nodes (blocks).
+*/
+struct NodeWriter {
+  sqlite3_int64 iBlock;           /* Current block id */
+  Blob key;                       /* Last key written to the current block */
+  Blob block;                     /* Current block image */
+};
+
+/*
+** An object of this type contains the state required to create or append
+** to an appendable b-tree segment.
+*/
+struct IncrmergeWriter {
+  int nLeafEst;                   /* Space allocated for leaf blocks */
+  int nWork;                      /* Number of leaf pages flushed */
+  sqlite3_int64 iAbsLevel;        /* Absolute level of input segments */
+  int iIdx;                       /* Index of *output* segment in iAbsLevel+1 */
+  sqlite3_int64 iStart;           /* Block number of first allocated block */
+  sqlite3_int64 iEnd;             /* Block number of last allocated block */
+  NodeWriter aNodeWriter[FTS_MAX_APPENDABLE_HEIGHT];
+};
+
+/*
+** An object of the following type is used to read data from a single
+** FTS segment node. See the following functions:
+**
+**     nodeReaderInit()
+**     nodeReaderNext()
+**     nodeReaderRelease()
+*/
+struct NodeReader {
+  const char *aNode;
+  int nNode;
+  int iOff;                       /* Current offset within aNode[] */
+
+  /* Output variables. Containing the current node entry. */
+  sqlite3_int64 iChild;           /* Pointer to child node */
+  Blob term;                      /* Current term */
+  const char *aDoclist;           /* Pointer to doclist */
+  int nDoclist;                   /* Size of doclist in bytes */
+};
+
+/*
+** If *pRc is not SQLITE_OK when this function is called, it is a no-op.
+** Otherwise, if the allocation at pBlob->a is not already at least nMin
+** bytes in size, extend (realloc) it to be so.
+**
+** If an OOM error occurs, set *pRc to SQLITE_NOMEM and leave pBlob->a
+** unmodified. Otherwise, if the allocation succeeds, update pBlob->nAlloc
+** to reflect the new size of the pBlob->a[] buffer.
+*/
+static void blobGrowBuffer(Blob *pBlob, int nMin, int *pRc){
+  if( *pRc==SQLITE_OK && nMin>pBlob->nAlloc ){
+    int nAlloc = nMin;
+    char *a = (char *)sqlite3_realloc(pBlob->a, nAlloc);
+    if( a ){
+      pBlob->nAlloc = nAlloc;
+      pBlob->a = a;
+    }else{
+      *pRc = SQLITE_NOMEM;
+    }
+  }
+}
+
+/*
+** Attempt to advance the node-reader object passed as the first argument to
+** the next entry on the node. 
+**
+** Return an error code if an error occurs (SQLITE_NOMEM is possible). 
+** Otherwise return SQLITE_OK. If there is no next entry on the node
+** (e.g. because the current entry is the last) set NodeReader->aNode to
+** NULL to indicate EOF. Otherwise, populate the NodeReader structure output 
+** variables for the new entry.
+*/
+static int nodeReaderNext(NodeReader *p){
+  int bFirst = (p->term.n==0);    /* True for first term on the node */
+  int nPrefix = 0;                /* Bytes to copy from previous term */
+  int nSuffix = 0;                /* Bytes to append to the prefix */
+  int rc = SQLITE_OK;             /* Return code */
+
+  assert( p->aNode );
+  if( p->iChild && bFirst==0 ) p->iChild++;
+  if( p->iOff>=p->nNode ){
+    /* EOF */
+    p->aNode = 0;
+  }else{
+    if( bFirst==0 ){
+      p->iOff += sqlite3Fts3GetVarint32(&p->aNode[p->iOff], &nPrefix);
+    }
+    p->iOff += sqlite3Fts3GetVarint32(&p->aNode[p->iOff], &nSuffix);
+
+    blobGrowBuffer(&p->term, nPrefix+nSuffix, &rc);
+    if( rc==SQLITE_OK ){
+      memcpy(&p->term.a[nPrefix], &p->aNode[p->iOff], nSuffix);
+      p->term.n = nPrefix+nSuffix;
+      p->iOff += nSuffix;
+      if( p->iChild==0 ){
+        p->iOff += sqlite3Fts3GetVarint32(&p->aNode[p->iOff], &p->nDoclist);
+        p->aDoclist = &p->aNode[p->iOff];
+        p->iOff += p->nDoclist;
+      }
+    }
+  }
+
+  assert( p->iOff<=p->nNode );
+
+  return rc;
+}
+
+/*
+** Release all dynamic resources held by node-reader object *p.
+*/
+static void nodeReaderRelease(NodeReader *p){
+  sqlite3_free(p->term.a);
+}
+
+/*
+** Initialize a node-reader object to read the node in buffer aNode/nNode.
+**
+** If successful, SQLITE_OK is returned and the NodeReader object set to 
+** point to the first entry on the node (if any). Otherwise, an SQLite
+** error code is returned.
+*/
+static int nodeReaderInit(NodeReader *p, const char *aNode, int nNode){
+  memset(p, 0, sizeof(NodeReader));
+  p->aNode = aNode;
+  p->nNode = nNode;
+
+  /* Figure out if this is a leaf or an internal node. */
+  if( p->aNode[0] ){
+    /* An internal node. */
+    p->iOff = 1 + sqlite3Fts3GetVarint(&p->aNode[1], &p->iChild);
+  }else{
+    p->iOff = 1;
+  }
+
+  return nodeReaderNext(p);
+}
+
+/*
+** This function is called while writing an FTS segment each time a leaf o
+** node is finished and written to disk. The key (zTerm/nTerm) is guaranteed
+** to be greater than the largest key on the node just written, but smaller
+** than or equal to the first key that will be written to the next leaf
+** node.
+**
+** The block id of the leaf node just written to disk may be found in
+** (pWriter->aNodeWriter[0].iBlock) when this function is called.
+*/
+static int fts3IncrmergePush(
+  Fts3Table *p,                   /* Fts3 table handle */
+  IncrmergeWriter *pWriter,       /* Writer object */
+  const char *zTerm,              /* Term to write to internal node */
+  int nTerm                       /* Bytes at zTerm */
+){
+  sqlite3_int64 iPtr = pWriter->aNodeWriter[0].iBlock;
+  int iLayer;
+
+  assert( nTerm>0 );
+  for(iLayer=1; ALWAYS(iLayer<FTS_MAX_APPENDABLE_HEIGHT); iLayer++){
+    sqlite3_int64 iNextPtr = 0;
+    NodeWriter *pNode = &pWriter->aNodeWriter[iLayer];
+    int rc = SQLITE_OK;
+    int nPrefix;
+    int nSuffix;
+    int nSpace;
+
+    /* Figure out how much space the key will consume if it is written to
+    ** the current node of layer iLayer. Due to the prefix compression, 
+    ** the space required changes depending on which node the key is to
+    ** be added to.  */
+    nPrefix = fts3PrefixCompress(pNode->key.a, pNode->key.n, zTerm, nTerm);
+    nSuffix = nTerm - nPrefix;
+    nSpace  = sqlite3Fts3VarintLen(nPrefix);
+    nSpace += sqlite3Fts3VarintLen(nSuffix) + nSuffix;
+
+    if( pNode->key.n==0 || (pNode->block.n + nSpace)<=p->nNodeSize ){ 
+      /* If the current node of layer iLayer contains zero keys, or if adding
+      ** the key to it will not cause it to grow to larger than nNodeSize 
+      ** bytes in size, write the key here.  */
+
+      Blob *pBlk = &pNode->block;
+      if( pBlk->n==0 ){
+        blobGrowBuffer(pBlk, p->nNodeSize, &rc);
+        if( rc==SQLITE_OK ){
+          pBlk->a[0] = (char)iLayer;
+          pBlk->n = 1 + sqlite3Fts3PutVarint(&pBlk->a[1], iPtr);
+        }
+      }
+      blobGrowBuffer(pBlk, pBlk->n + nSpace, &rc);
+      blobGrowBuffer(&pNode->key, nTerm, &rc);
+
+      if( rc==SQLITE_OK ){
+        if( pNode->key.n ){
+          pBlk->n += sqlite3Fts3PutVarint(&pBlk->a[pBlk->n], nPrefix);
+        }
+        pBlk->n += sqlite3Fts3PutVarint(&pBlk->a[pBlk->n], nSuffix);
+        memcpy(&pBlk->a[pBlk->n], &zTerm[nPrefix], nSuffix);
+        pBlk->n += nSuffix;
+
+        memcpy(pNode->key.a, zTerm, nTerm);
+        pNode->key.n = nTerm;
+      }
+    }else{
+      /* Otherwise, flush the current node of layer iLayer to disk.
+      ** Then allocate a new, empty sibling node. The key will be written
+      ** into the parent of this node. */
+      rc = fts3WriteSegment(p, pNode->iBlock, pNode->block.a, pNode->block.n);
+
+      assert( pNode->block.nAlloc>=p->nNodeSize );
+      pNode->block.a[0] = (char)iLayer;
+      pNode->block.n = 1 + sqlite3Fts3PutVarint(&pNode->block.a[1], iPtr+1);
+
+      iNextPtr = pNode->iBlock;
+      pNode->iBlock++;
+      pNode->key.n = 0;
+    }
+
+    if( rc!=SQLITE_OK || iNextPtr==0 ) return rc;
+    iPtr = iNextPtr;
+  }
+
+  assert( 0 );
+  return 0;
+}
+
+/*
+** Append a term and (optionally) doclist to the FTS segment node currently
+** stored in blob *pNode. The node need not contain any terms, but the
+** header must be written before this function is called.
+**
+** A node header is a single 0x00 byte for a leaf node, or a height varint
+** followed by the left-hand-child varint for an internal node.
+**
+** The term to be appended is passed via arguments zTerm/nTerm. For a 
+** leaf node, the doclist is passed as aDoclist/nDoclist. For an internal
+** node, both aDoclist and nDoclist must be passed 0.
+**
+** If the size of the value in blob pPrev is zero, then this is the first
+** term written to the node. Otherwise, pPrev contains a copy of the 
+** previous term. Before this function returns, it is updated to contain a
+** copy of zTerm/nTerm.
+**
+** It is assumed that the buffer associated with pNode is already large
+** enough to accommodate the new entry. The buffer associated with pPrev
+** is extended by this function if requrired.
+**
+** If an error (i.e. OOM condition) occurs, an SQLite error code is
+** returned. Otherwise, SQLITE_OK.
+*/
+static int fts3AppendToNode(
+  Blob *pNode,                    /* Current node image to append to */
+  Blob *pPrev,                    /* Buffer containing previous term written */
+  const char *zTerm,              /* New term to write */
+  int nTerm,                      /* Size of zTerm in bytes */
+  const char *aDoclist,           /* Doclist (or NULL) to write */
+  int nDoclist                    /* Size of aDoclist in bytes */ 
+){
+  int rc = SQLITE_OK;             /* Return code */
+  int bFirst = (pPrev->n==0);     /* True if this is the first term written */
+  int nPrefix;                    /* Size of term prefix in bytes */
+  int nSuffix;                    /* Size of term suffix in bytes */
+
+  /* Node must have already been started. There must be a doclist for a
+  ** leaf node, and there must not be a doclist for an internal node.  */
+  assert( pNode->n>0 );
+  assert( (pNode->a[0]=='\0')==(aDoclist!=0) );
+
+  blobGrowBuffer(pPrev, nTerm, &rc);
+  if( rc!=SQLITE_OK ) return rc;
+
+  nPrefix = fts3PrefixCompress(pPrev->a, pPrev->n, zTerm, nTerm);
+  nSuffix = nTerm - nPrefix;
+  memcpy(pPrev->a, zTerm, nTerm);
+  pPrev->n = nTerm;
+
+  if( bFirst==0 ){
+    pNode->n += sqlite3Fts3PutVarint(&pNode->a[pNode->n], nPrefix);
+  }
+  pNode->n += sqlite3Fts3PutVarint(&pNode->a[pNode->n], nSuffix);
+  memcpy(&pNode->a[pNode->n], &zTerm[nPrefix], nSuffix);
+  pNode->n += nSuffix;
+
+  if( aDoclist ){
+    pNode->n += sqlite3Fts3PutVarint(&pNode->a[pNode->n], nDoclist);
+    memcpy(&pNode->a[pNode->n], aDoclist, nDoclist);
+    pNode->n += nDoclist;
+  }
+
+  assert( pNode->n<=pNode->nAlloc );
+
+  return SQLITE_OK;
+}
+
+/*
+** Append the current term and doclist pointed to by cursor pCsr to the
+** appendable b-tree segment opened for writing by pWriter.
+**
+** Return SQLITE_OK if successful, or an SQLite error code otherwise.
+*/
+static int fts3IncrmergeAppend(
+  Fts3Table *p,                   /* Fts3 table handle */
+  IncrmergeWriter *pWriter,       /* Writer object */
+  Fts3MultiSegReader *pCsr        /* Cursor containing term and doclist */
+){
+  const char *zTerm = pCsr->zTerm;
+  int nTerm = pCsr->nTerm;
+  const char *aDoclist = pCsr->aDoclist;
+  int nDoclist = pCsr->nDoclist;
+  int rc = SQLITE_OK;           /* Return code */
+  int nSpace;                   /* Total space in bytes required on leaf */
+  int nPrefix;                  /* Size of prefix shared with previous term */
+  int nSuffix;                  /* Size of suffix (nTerm - nPrefix) */
+  NodeWriter *pLeaf;            /* Object used to write leaf nodes */
+
+  pLeaf = &pWriter->aNodeWriter[0];
+  nPrefix = fts3PrefixCompress(pLeaf->key.a, pLeaf->key.n, zTerm, nTerm);
+  nSuffix = nTerm - nPrefix;
+
+  nSpace  = sqlite3Fts3VarintLen(nPrefix);
+  nSpace += sqlite3Fts3VarintLen(nSuffix) + nSuffix;
+  nSpace += sqlite3Fts3VarintLen(nDoclist) + nDoclist;
+
+  /* If the current block is not empty, and if adding this term/doclist
+  ** to the current block would make it larger than Fts3Table.nNodeSize
+  ** bytes, write this block out to the database. */
+  if( pLeaf->block.n>0 && (pLeaf->block.n + nSpace)>p->nNodeSize ){
+    rc = fts3WriteSegment(p, pLeaf->iBlock, pLeaf->block.a, pLeaf->block.n);
+    pWriter->nWork++;
+
+    /* Add the current term to the parent node. The term added to the 
+    ** parent must:
+    **
+    **   a) be greater than the largest term on the leaf node just written
+    **      to the database (still available in pLeaf->key), and
+    **
+    **   b) be less than or equal to the term about to be added to the new
+    **      leaf node (zTerm/nTerm).
+    **
+    ** In other words, it must be the prefix of zTerm 1 byte longer than
+    ** the common prefix (if any) of zTerm and pWriter->zTerm.
+    */
+    if( rc==SQLITE_OK ){
+      rc = fts3IncrmergePush(p, pWriter, zTerm, nPrefix+1);
+    }
+
+    /* Advance to the next output block */
+    pLeaf->iBlock++;
+    pLeaf->key.n = 0;
+    pLeaf->block.n = 0;
+
+    nSuffix = nTerm;
+    nSpace  = 1;
+    nSpace += sqlite3Fts3VarintLen(nSuffix) + nSuffix;
+    nSpace += sqlite3Fts3VarintLen(nDoclist) + nDoclist;
+  }
+
+  blobGrowBuffer(&pLeaf->block, pLeaf->block.n + nSpace, &rc);
+
+  if( rc==SQLITE_OK ){
+    if( pLeaf->block.n==0 ){
+      pLeaf->block.n = 1;
+      pLeaf->block.a[0] = '\0';
+    }
+    rc = fts3AppendToNode(
+        &pLeaf->block, &pLeaf->key, zTerm, nTerm, aDoclist, nDoclist
+    );
+  }
+
+  return rc;
+}
+
+/*
+** This function is called to release all dynamic resources held by the
+** merge-writer object pWriter, and if no error has occurred, to flush
+** all outstanding node buffers held by pWriter to disk.
+**
+** If *pRc is not SQLITE_OK when this function is called, then no attempt
+** is made to write any data to disk. Instead, this function serves only
+** to release outstanding resources.
+**
+** Otherwise, if *pRc is initially SQLITE_OK and an error occurs while
+** flushing buffers to disk, *pRc is set to an SQLite error code before
+** returning.
+*/
+static void fts3IncrmergeRelease(
+  Fts3Table *p,                   /* FTS3 table handle */
+  IncrmergeWriter *pWriter,       /* Merge-writer object */
+  int *pRc                        /* IN/OUT: Error code */
+){
+  int i;                          /* Used to iterate through non-root layers */
+  int iRoot;                      /* Index of root in pWriter->aNodeWriter */
+  NodeWriter *pRoot;              /* NodeWriter for root node */
+  int rc = *pRc;                  /* Error code */
+
+  /* Set iRoot to the index in pWriter->aNodeWriter[] of the output segment 
+  ** root node. If the segment fits entirely on a single leaf node, iRoot
+  ** will be set to 0. If the root node is the parent of the leaves, iRoot
+  ** will be 1. And so on.  */
+  for(iRoot=FTS_MAX_APPENDABLE_HEIGHT-1; iRoot>=0; iRoot--){
+    NodeWriter *pNode = &pWriter->aNodeWriter[iRoot];
+    if( pNode->block.n>0 ) break;
+    assert( *pRc || pNode->block.nAlloc==0 );
+    assert( *pRc || pNode->key.nAlloc==0 );
+    sqlite3_free(pNode->block.a);
+    sqlite3_free(pNode->key.a);
+  }
+
+  /* Empty output segment. This is a no-op. */
+  if( iRoot<0 ) return;
+
+  /* The entire output segment fits on a single node. Normally, this means
+  ** the node would be stored as a blob in the "root" column of the %_segdir
+  ** table. However, this is not permitted in this case. The problem is that 
+  ** space has already been reserved in the %_segments table, and so the 
+  ** start_block and end_block fields of the %_segdir table must be populated. 
+  ** And, by design or by accident, released versions of FTS cannot handle 
+  ** segments that fit entirely on the root node with start_block!=0.
+  **
+  ** Instead, create a synthetic root node that contains nothing but a 
+  ** pointer to the single content node. So that the segment consists of a
+  ** single leaf and a single interior (root) node.
+  **
+  ** Todo: Better might be to defer allocating space in the %_segments 
+  ** table until we are sure it is needed.
+  */
+  if( iRoot==0 ){
+    Blob *pBlock = &pWriter->aNodeWriter[1].block;
+    blobGrowBuffer(pBlock, 1 + FTS3_VARINT_MAX, &rc);
+    if( rc==SQLITE_OK ){
+      pBlock->a[0] = 0x01;
+      pBlock->n = 1 + sqlite3Fts3PutVarint(
+          &pBlock->a[1], pWriter->aNodeWriter[0].iBlock
+      );
+    }
+    iRoot = 1;
+  }
+  pRoot = &pWriter->aNodeWriter[iRoot];
+
+  /* Flush all currently outstanding nodes to disk. */
+  for(i=0; i<iRoot; i++){
+    NodeWriter *pNode = &pWriter->aNodeWriter[i];
+    if( pNode->block.n>0 && rc==SQLITE_OK ){
+      rc = fts3WriteSegment(p, pNode->iBlock, pNode->block.a, pNode->block.n);
+    }
+    sqlite3_free(pNode->block.a);
+    sqlite3_free(pNode->key.a);
+  }
+
+  /* Write the %_segdir record. */
+  if( rc==SQLITE_OK ){
+    rc = fts3WriteSegdir(p, 
+        pWriter->iAbsLevel+1,               /* level */
+        pWriter->iIdx,                      /* idx */
+        pWriter->iStart,                    /* start_block */
+        pWriter->aNodeWriter[0].iBlock,     /* leaves_end_block */
+        pWriter->iEnd,                      /* end_block */
+        pRoot->block.a, pRoot->block.n      /* root */
+    );
+  }
+  sqlite3_free(pRoot->block.a);
+  sqlite3_free(pRoot->key.a);
+
+  *pRc = rc;
+}
+
+/*
+** Compare the term in buffer zLhs (size in bytes nLhs) with that in
+** zRhs (size in bytes nRhs) using memcmp. If one term is a prefix of
+** the other, it is considered to be smaller than the other.
+**
+** Return -ve if zLhs is smaller than zRhs, 0 if it is equal, or +ve
+** if it is greater.
+*/
+static int fts3TermCmp(
+  const char *zLhs, int nLhs,     /* LHS of comparison */
+  const char *zRhs, int nRhs      /* RHS of comparison */
+){
+  int nCmp = MIN(nLhs, nRhs);
+  int res;
+
+  res = memcmp(zLhs, zRhs, nCmp);
+  if( res==0 ) res = nLhs - nRhs;
+
+  return res;
+}
+
+
+/*
+** Query to see if the entry in the %_segments table with blockid iEnd is 
+** NULL. If no error occurs and the entry is NULL, set *pbRes 1 before
+** returning. Otherwise, set *pbRes to 0. 
+**
+** Or, if an error occurs while querying the database, return an SQLite 
+** error code. The final value of *pbRes is undefined in this case.
+**
+** This is used to test if a segment is an "appendable" segment. If it
+** is, then a NULL entry has been inserted into the %_segments table
+** with blockid %_segdir.end_block.
+*/
+static int fts3IsAppendable(Fts3Table *p, sqlite3_int64 iEnd, int *pbRes){
+  int bRes = 0;                   /* Result to set *pbRes to */
+  sqlite3_stmt *pCheck = 0;       /* Statement to query database with */
+  int rc;                         /* Return code */
+
+  rc = fts3SqlStmt(p, SQL_SEGMENT_IS_APPENDABLE, &pCheck, 0);
+  if( rc==SQLITE_OK ){
+    sqlite3_bind_int64(pCheck, 1, iEnd);
+    if( SQLITE_ROW==sqlite3_step(pCheck) ) bRes = 1;
+    rc = sqlite3_reset(pCheck);
+  }
+  
+  *pbRes = bRes;
+  return rc;
+}
+
+/*
+** This function is called when initializing an incremental-merge operation.
+** It checks if the existing segment with index value iIdx at absolute level 
+** (iAbsLevel+1) can be appended to by the incremental merge. If it can, the
+** merge-writer object *pWriter is initialized to write to it.
+**
+** An existing segment can be appended to by an incremental merge if:
+**
+**   * It was initially created as an appendable segment (with all required
+**     space pre-allocated), and
+**
+**   * The first key read from the input (arguments zKey and nKey) is 
+**     greater than the largest key currently stored in the potential
+**     output segment.
+*/
+static int fts3IncrmergeLoad(
+  Fts3Table *p,                   /* Fts3 table handle */
+  sqlite3_int64 iAbsLevel,        /* Absolute level of input segments */
+  int iIdx,                       /* Index of candidate output segment */
+  const char *zKey,               /* First key to write */
+  int nKey,                       /* Number of bytes in nKey */
+  IncrmergeWriter *pWriter        /* Populate this object */
+){
+  int rc;                         /* Return code */
+  sqlite3_stmt *pSelect = 0;      /* SELECT to read %_segdir entry */
+
+  rc = fts3SqlStmt(p, SQL_SELECT_SEGDIR, &pSelect, 0);
+  if( rc==SQLITE_OK ){
+    sqlite3_int64 iStart = 0;     /* Value of %_segdir.start_block */
+    sqlite3_int64 iLeafEnd = 0;   /* Value of %_segdir.leaves_end_block */
+    sqlite3_int64 iEnd = 0;       /* Value of %_segdir.end_block */
+    const char *aRoot = 0;        /* Pointer to %_segdir.root buffer */
+    int nRoot = 0;                /* Size of aRoot[] in bytes */
+    int rc2;                      /* Return code from sqlite3_reset() */
+    int bAppendable = 0;          /* Set to true if segment is appendable */
+
+    /* Read the %_segdir entry for index iIdx absolute level (iAbsLevel+1) */
+    sqlite3_bind_int64(pSelect, 1, iAbsLevel+1);
+    sqlite3_bind_int(pSelect, 2, iIdx);
+    if( sqlite3_step(pSelect)==SQLITE_ROW ){
+      iStart = sqlite3_column_int64(pSelect, 1);
+      iLeafEnd = sqlite3_column_int64(pSelect, 2);
+      iEnd = sqlite3_column_int64(pSelect, 3);
+      nRoot = sqlite3_column_bytes(pSelect, 4);
+      aRoot = sqlite3_column_blob(pSelect, 4);
+    }else{
+      return sqlite3_reset(pSelect);
+    }
+
+    /* Check for the zero-length marker in the %_segments table */
+    rc = fts3IsAppendable(p, iEnd, &bAppendable);
+
+    /* Check that zKey/nKey is larger than the largest key the candidate */
+    if( rc==SQLITE_OK && bAppendable ){
+      char *aLeaf = 0;
+      int nLeaf = 0;
+
+      rc = sqlite3Fts3ReadBlock(p, iLeafEnd, &aLeaf, &nLeaf, 0);
+      if( rc==SQLITE_OK ){
+        NodeReader reader;
+        for(rc = nodeReaderInit(&reader, aLeaf, nLeaf);
+            rc==SQLITE_OK && reader.aNode;
+            rc = nodeReaderNext(&reader)
+        ){
+          assert( reader.aNode );
+        }
+        if( fts3TermCmp(zKey, nKey, reader.term.a, reader.term.n)<=0 ){
+          bAppendable = 0;
+        }
+        nodeReaderRelease(&reader);
+      }
+      sqlite3_free(aLeaf);
+    }
+
+    if( rc==SQLITE_OK && bAppendable ){
+      /* It is possible to append to this segment. Set up the IncrmergeWriter
+      ** object to do so.  */
+      int i;
+      int nHeight = (int)aRoot[0];
+      NodeWriter *pNode;
+
+      pWriter->nLeafEst = (int)((iEnd - iStart) + 1)/FTS_MAX_APPENDABLE_HEIGHT;
+      pWriter->iStart = iStart;
+      pWriter->iEnd = iEnd;
+      pWriter->iAbsLevel = iAbsLevel;
+      pWriter->iIdx = iIdx;
+
+      for(i=nHeight+1; i<FTS_MAX_APPENDABLE_HEIGHT; i++){
+        pWriter->aNodeWriter[i].iBlock = pWriter->iStart + i*pWriter->nLeafEst;
+      }
+
+      pNode = &pWriter->aNodeWriter[nHeight];
+      pNode->iBlock = pWriter->iStart + pWriter->nLeafEst*nHeight;
+      blobGrowBuffer(&pNode->block, MAX(nRoot, p->nNodeSize), &rc);
+      if( rc==SQLITE_OK ){
+        memcpy(pNode->block.a, aRoot, nRoot);
+        pNode->block.n = nRoot;
+      }
+
+      for(i=nHeight; i>=0 && rc==SQLITE_OK; i--){
+        NodeReader reader;
+        pNode = &pWriter->aNodeWriter[i];
+
+        rc = nodeReaderInit(&reader, pNode->block.a, pNode->block.n);
+        while( reader.aNode && rc==SQLITE_OK ) rc = nodeReaderNext(&reader);
+        blobGrowBuffer(&pNode->key, reader.term.n, &rc);
+        if( rc==SQLITE_OK ){
+          memcpy(pNode->key.a, reader.term.a, reader.term.n);
+          pNode->key.n = reader.term.n;
+          if( i>0 ){
+            char *aBlock = 0;
+            int nBlock = 0;
+            pNode = &pWriter->aNodeWriter[i-1];
+            pNode->iBlock = reader.iChild;
+            rc = sqlite3Fts3ReadBlock(p, reader.iChild, &aBlock, &nBlock, 0);
+            blobGrowBuffer(&pNode->block, MAX(nBlock, p->nNodeSize), &rc);
+            if( rc==SQLITE_OK ){
+              memcpy(pNode->block.a, aBlock, nBlock);
+              pNode->block.n = nBlock;
+            }
+            sqlite3_free(aBlock);
+          }
+        }
+        nodeReaderRelease(&reader);
+      }
+    }
+
+    rc2 = sqlite3_reset(pSelect);
+    if( rc==SQLITE_OK ) rc = rc2;
+  }
+
+  return rc;
+}
+
+/*
+** Determine the largest segment index value that exists within absolute
+** level iAbsLevel+1. If no error occurs, set *piIdx to this value plus
+** one before returning SQLITE_OK. Or, if there are no segments at all 
+** within level iAbsLevel, set *piIdx to zero.
+**
+** If an error occurs, return an SQLite error code. The final value of
+** *piIdx is undefined in this case.
+*/
+static int fts3IncrmergeOutputIdx( 
+  Fts3Table *p,                   /* FTS Table handle */
+  sqlite3_int64 iAbsLevel,        /* Absolute index of input segments */
+  int *piIdx                      /* OUT: Next free index at iAbsLevel+1 */
+){
+  int rc;
+  sqlite3_stmt *pOutputIdx = 0;   /* SQL used to find output index */
+
+  rc = fts3SqlStmt(p, SQL_NEXT_SEGMENT_INDEX, &pOutputIdx, 0);
+  if( rc==SQLITE_OK ){
+    sqlite3_bind_int64(pOutputIdx, 1, iAbsLevel+1);
+    sqlite3_step(pOutputIdx);
+    *piIdx = sqlite3_column_int(pOutputIdx, 0);
+    rc = sqlite3_reset(pOutputIdx);
+  }
+
+  return rc;
+}
+
+/* 
+** Allocate an appendable output segment on absolute level iAbsLevel+1
+** with idx value iIdx.
+**
+** In the %_segdir table, a segment is defined by the values in three
+** columns:
+**
+**     start_block
+**     leaves_end_block
+**     end_block
+**
+** When an appendable segment is allocated, it is estimated that the
+** maximum number of leaf blocks that may be required is the sum of the
+** number of leaf blocks consumed by the input segments, plus the number
+** of input segments, multiplied by two. This value is stored in stack 
+** variable nLeafEst.
+**
+** A total of 16*nLeafEst blocks are allocated when an appendable segment
+** is created ((1 + end_block - start_block)==16*nLeafEst). The contiguous
+** array of leaf nodes starts at the first block allocated. The array
+** of interior nodes that are parents of the leaf nodes start at block
+** (start_block + (1 + end_block - start_block) / 16). And so on.
+**
+** In the actual code below, the value "16" is replaced with the 
+** pre-processor macro FTS_MAX_APPENDABLE_HEIGHT.
+*/
+static int fts3IncrmergeWriter( 
+  Fts3Table *p,                   /* Fts3 table handle */
+  sqlite3_int64 iAbsLevel,        /* Absolute level of input segments */
+  int iIdx,                       /* Index of new output segment */
+  Fts3MultiSegReader *pCsr,       /* Cursor that data will be read from */
+  IncrmergeWriter *pWriter        /* Populate this object */
+){
+  int rc;                         /* Return Code */
+  int i;                          /* Iterator variable */
+  int nLeafEst = 0;               /* Blocks allocated for leaf nodes */
+  sqlite3_stmt *pLeafEst = 0;     /* SQL used to determine nLeafEst */
+  sqlite3_stmt *pFirstBlock = 0;  /* SQL used to determine first block */
+
+  /* Calculate nLeafEst. */
+  rc = fts3SqlStmt(p, SQL_MAX_LEAF_NODE_ESTIMATE, &pLeafEst, 0);
+  if( rc==SQLITE_OK ){
+    sqlite3_bind_int64(pLeafEst, 1, iAbsLevel);
+    sqlite3_bind_int64(pLeafEst, 2, pCsr->nSegment);
+    if( SQLITE_ROW==sqlite3_step(pLeafEst) ){
+      nLeafEst = sqlite3_column_int(pLeafEst, 0);
+    }
+    rc = sqlite3_reset(pLeafEst);
+  }
+  if( rc!=SQLITE_OK ) return rc;
+
+  /* Calculate the first block to use in the output segment */
+  rc = fts3SqlStmt(p, SQL_NEXT_SEGMENTS_ID, &pFirstBlock, 0);
+  if( rc==SQLITE_OK ){
+    if( SQLITE_ROW==sqlite3_step(pFirstBlock) ){
+      pWriter->iStart = sqlite3_column_int64(pFirstBlock, 0);
+      pWriter->iEnd = pWriter->iStart - 1;
+      pWriter->iEnd += nLeafEst * FTS_MAX_APPENDABLE_HEIGHT;
+    }
+    rc = sqlite3_reset(pFirstBlock);
+  }
+  if( rc!=SQLITE_OK ) return rc;
+
+  /* Insert the marker in the %_segments table to make sure nobody tries
+  ** to steal the space just allocated. This is also used to identify 
+  ** appendable segments.  */
+  rc = fts3WriteSegment(p, pWriter->iEnd, 0, 0);
+  if( rc!=SQLITE_OK ) return rc;
+
+  pWriter->iAbsLevel = iAbsLevel;
+  pWriter->nLeafEst = nLeafEst;
+  pWriter->iIdx = iIdx;
+
+  /* Set up the array of NodeWriter objects */
+  for(i=0; i<FTS_MAX_APPENDABLE_HEIGHT; i++){
+    pWriter->aNodeWriter[i].iBlock = pWriter->iStart + i*pWriter->nLeafEst;
+  }
+  return SQLITE_OK;
+}
+
+/*
+** Remove an entry from the %_segdir table. This involves running the 
+** following two statements:
+**
+**   DELETE FROM %_segdir WHERE level = :iAbsLevel AND idx = :iIdx
+**   UPDATE %_segdir SET idx = idx - 1 WHERE level = :iAbsLevel AND idx > :iIdx
+**
+** The DELETE statement removes the specific %_segdir level. The UPDATE 
+** statement ensures that the remaining segments have contiguously allocated
+** idx values.
+*/
+static int fts3RemoveSegdirEntry(
+  Fts3Table *p,                   /* FTS3 table handle */
+  sqlite3_int64 iAbsLevel,        /* Absolute level to delete from */
+  int iIdx                        /* Index of %_segdir entry to delete */
+){
+  int rc;                         /* Return code */
+  sqlite3_stmt *pDelete = 0;      /* DELETE statement */
+
+  rc = fts3SqlStmt(p, SQL_DELETE_SEGDIR_ENTRY, &pDelete, 0);
+  if( rc==SQLITE_OK ){
+    sqlite3_bind_int64(pDelete, 1, iAbsLevel);
+    sqlite3_bind_int(pDelete, 2, iIdx);
+    sqlite3_step(pDelete);
+    rc = sqlite3_reset(pDelete);
+  }
+
+  return rc;
+}
+
+/*
+** One or more segments have just been removed from absolute level iAbsLevel.
+** Update the 'idx' values of the remaining segments in the level so that
+** the idx values are a contiguous sequence starting from 0.
+*/
+static int fts3RepackSegdirLevel(
+  Fts3Table *p,                   /* FTS3 table handle */
+  sqlite3_int64 iAbsLevel         /* Absolute level to repack */
+){
+  int rc;                         /* Return code */
+  int *aIdx = 0;                  /* Array of remaining idx values */
+  int nIdx = 0;                   /* Valid entries in aIdx[] */
+  int nAlloc = 0;                 /* Allocated size of aIdx[] */
+  int i;                          /* Iterator variable */
+  sqlite3_stmt *pSelect = 0;      /* Select statement to read idx values */
+  sqlite3_stmt *pUpdate = 0;      /* Update statement to modify idx values */
+
+  rc = fts3SqlStmt(p, SQL_SELECT_INDEXES, &pSelect, 0);
+  if( rc==SQLITE_OK ){
+    int rc2;
+    sqlite3_bind_int64(pSelect, 1, iAbsLevel);
+    while( SQLITE_ROW==sqlite3_step(pSelect) ){
+      if( nIdx>=nAlloc ){
+        int *aNew;
+        nAlloc += 16;
+        aNew = sqlite3_realloc(aIdx, nAlloc*sizeof(int));
+        if( !aNew ){
+          rc = SQLITE_NOMEM;
+          break;
+        }
+        aIdx = aNew;
+      }
+      aIdx[nIdx++] = sqlite3_column_int(pSelect, 0);
+    }
+    rc2 = sqlite3_reset(pSelect);
+    if( rc==SQLITE_OK ) rc = rc2;
+  }
+
+  if( rc==SQLITE_OK ){
+    rc = fts3SqlStmt(p, SQL_SHIFT_SEGDIR_ENTRY, &pUpdate, 0);
+  }
+  if( rc==SQLITE_OK ){
+    sqlite3_bind_int64(pUpdate, 2, iAbsLevel);
+  }
+
+  assert( p->bIgnoreSavepoint==0 );
+  p->bIgnoreSavepoint = 1;
+  for(i=0; rc==SQLITE_OK && i<nIdx; i++){
+    if( aIdx[i]!=i ){
+      sqlite3_bind_int(pUpdate, 3, aIdx[i]);
+      sqlite3_bind_int(pUpdate, 1, i);
+      sqlite3_step(pUpdate);
+      rc = sqlite3_reset(pUpdate);
+    }
+  }
+  p->bIgnoreSavepoint = 0;
+
+  sqlite3_free(aIdx);
+  return rc;
+}
+
+static void fts3StartNode(Blob *pNode, int iHeight, sqlite3_int64 iChild){
+  pNode->a[0] = (char)iHeight;
+  if( iChild ){
+    assert( pNode->nAlloc>=1+sqlite3Fts3VarintLen(iChild) );
+    pNode->n = 1 + sqlite3Fts3PutVarint(&pNode->a[1], iChild);
+  }else{
+    assert( pNode->nAlloc>=1 );
+    pNode->n = 1;
+  }
+}
+
+/*
+** The first two arguments are a pointer to and the size of a segment b-tree
+** node. The node may be a leaf or an internal node.
+**
+** This function creates a new node image in blob object *pNew by copying
+** all terms that are greater than or equal to zTerm/nTerm (for leaf nodes)
+** or greater than zTerm/nTerm (for internal nodes) from aNode/nNode.
+*/
+static int fts3TruncateNode(
+  const char *aNode,              /* Current node image */
+  int nNode,                      /* Size of aNode in bytes */
+  Blob *pNew,                     /* OUT: Write new node image here */
+  const char *zTerm,              /* Omit all terms smaller than this */
+  int nTerm,                      /* Size of zTerm in bytes */
+  sqlite3_int64 *piBlock          /* OUT: Block number in next layer down */
+){
+  NodeReader reader;              /* Reader object */
+  Blob prev = {0, 0, 0};          /* Previous term written to new node */
+  int rc = SQLITE_OK;             /* Return code */
+  int bLeaf = aNode[0]=='\0';     /* True for a leaf node */
+
+  /* Allocate required output space */
+  blobGrowBuffer(pNew, nNode, &rc);
+  if( rc!=SQLITE_OK ) return rc;
+  pNew->n = 0;
+
+  /* Populate new node buffer */
+  for(rc = nodeReaderInit(&reader, aNode, nNode); 
+      rc==SQLITE_OK && reader.aNode; 
+      rc = nodeReaderNext(&reader)
+  ){
+    if( pNew->n==0 ){
+      int res = fts3TermCmp(reader.term.a, reader.term.n, zTerm, nTerm);
+      if( res<0 || (bLeaf==0 && res==0) ) continue;
+      fts3StartNode(pNew, (int)aNode[0], reader.iChild);
+      *piBlock = reader.iChild;
+    }
+    rc = fts3AppendToNode(
+        pNew, &prev, reader.term.a, reader.term.n,
+        reader.aDoclist, reader.nDoclist
+    );
+    if( rc!=SQLITE_OK ) break;
+  }
+  if( pNew->n==0 ){
+    fts3StartNode(pNew, (int)aNode[0], reader.iChild);
+    *piBlock = reader.iChild;
+  }
+  assert( pNew->n<=pNew->nAlloc );
+
+  nodeReaderRelease(&reader);
+  sqlite3_free(prev.a);
+  return rc;
+}
+
+/*
+** Remove all terms smaller than zTerm/nTerm from segment iIdx in absolute 
+** level iAbsLevel. This may involve deleting entries from the %_segments
+** table, and modifying existing entries in both the %_segments and %_segdir
+** tables.
+**
+** SQLITE_OK is returned if the segment is updated successfully. Or an
+** SQLite error code otherwise.
+*/
+static int fts3TruncateSegment(
+  Fts3Table *p,                   /* FTS3 table handle */
+  sqlite3_int64 iAbsLevel,        /* Absolute level of segment to modify */
+  int iIdx,                       /* Index within level of segment to modify */
+  const char *zTerm,              /* Remove terms smaller than this */
+  int nTerm                      /* Number of bytes in buffer zTerm */
+){
+  int rc = SQLITE_OK;             /* Return code */
+  Blob root = {0,0,0};            /* New root page image */
+  Blob block = {0,0,0};           /* Buffer used for any other block */
+  sqlite3_int64 iBlock = 0;       /* Block id */
+  sqlite3_int64 iNewStart = 0;    /* New value for iStartBlock */
+  sqlite3_int64 iOldStart = 0;    /* Old value for iStartBlock */
+  sqlite3_stmt *pFetch = 0;       /* Statement used to fetch segdir */
+
+  rc = fts3SqlStmt(p, SQL_SELECT_SEGDIR, &pFetch, 0);
+  if( rc==SQLITE_OK ){
+    int rc2;                      /* sqlite3_reset() return code */
+    sqlite3_bind_int64(pFetch, 1, iAbsLevel);
+    sqlite3_bind_int(pFetch, 2, iIdx);
+    if( SQLITE_ROW==sqlite3_step(pFetch) ){
+      const char *aRoot = sqlite3_column_blob(pFetch, 4);
+      int nRoot = sqlite3_column_bytes(pFetch, 4);
+      iOldStart = sqlite3_column_int64(pFetch, 1);
+      rc = fts3TruncateNode(aRoot, nRoot, &root, zTerm, nTerm, &iBlock);
+    }
+    rc2 = sqlite3_reset(pFetch);
+    if( rc==SQLITE_OK ) rc = rc2;
+  }
+
+  while( rc==SQLITE_OK && iBlock ){
+    char *aBlock = 0;
+    int nBlock = 0;
+    iNewStart = iBlock;
+
+    rc = sqlite3Fts3ReadBlock(p, iBlock, &aBlock, &nBlock, 0);
+    if( rc==SQLITE_OK ){
+      rc = fts3TruncateNode(aBlock, nBlock, &block, zTerm, nTerm, &iBlock);
+    }
+    if( rc==SQLITE_OK ){
+      rc = fts3WriteSegment(p, iNewStart, block.a, block.n);
+    }
+    sqlite3_free(aBlock);
+  }
+
+  /* Variable iNewStart now contains the first valid leaf node. */
+  if( rc==SQLITE_OK && iNewStart ){
+    sqlite3_stmt *pDel = 0;
+    rc = fts3SqlStmt(p, SQL_DELETE_SEGMENTS_RANGE, &pDel, 0);
+    if( rc==SQLITE_OK ){
+      sqlite3_bind_int64(pDel, 1, iOldStart);
+      sqlite3_bind_int64(pDel, 2, iNewStart-1);
+      sqlite3_step(pDel);
+      rc = sqlite3_reset(pDel);
+    }
+  }
+
+  if( rc==SQLITE_OK ){
+    sqlite3_stmt *pChomp = 0;
+    rc = fts3SqlStmt(p, SQL_CHOMP_SEGDIR, &pChomp, 0);
+    if( rc==SQLITE_OK ){
+      sqlite3_bind_int64(pChomp, 1, iNewStart);
+      sqlite3_bind_blob(pChomp, 2, root.a, root.n, SQLITE_STATIC);
+      sqlite3_bind_int64(pChomp, 3, iAbsLevel);
+      sqlite3_bind_int(pChomp, 4, iIdx);
+      sqlite3_step(pChomp);
+      rc = sqlite3_reset(pChomp);
+    }
+  }
+
+  sqlite3_free(root.a);
+  sqlite3_free(block.a);
+  return rc;
+}
+
+/*
+** This function is called after an incrmental-merge operation has run to
+** merge (or partially merge) two or more segments from absolute level
+** iAbsLevel.
+**
+** Each input segment is either removed from the db completely (if all of
+** its data was copied to the output segment by the incrmerge operation)
+** or modified in place so that it no longer contains those entries that
+** have been duplicated in the output segment.
+*/
+static int fts3IncrmergeChomp(
+  Fts3Table *p,                   /* FTS table handle */
+  sqlite3_int64 iAbsLevel,        /* Absolute level containing segments */
+  Fts3MultiSegReader *pCsr,       /* Chomp all segments opened by this cursor */
+  int *pnRem                      /* Number of segments not deleted */
+){
+  int i;
+  int nRem = 0;
+  int rc = SQLITE_OK;
+
+  for(i=pCsr->nSegment-1; i>=0 && rc==SQLITE_OK; i--){
+    Fts3SegReader *pSeg = 0;
+    int j;
+
+    /* Find the Fts3SegReader object with Fts3SegReader.iIdx==i. It is hiding
+    ** somewhere in the pCsr->apSegment[] array.  */
+    for(j=0; ALWAYS(j<pCsr->nSegment); j++){
+      pSeg = pCsr->apSegment[j];
+      if( pSeg->iIdx==i ) break;
+    }
+    assert( j<pCsr->nSegment && pSeg->iIdx==i );
+
+    if( pSeg->aNode==0 ){
+      /* Seg-reader is at EOF. Remove the entire input segment. */
+      rc = fts3DeleteSegment(p, pSeg);
+      if( rc==SQLITE_OK ){
+        rc = fts3RemoveSegdirEntry(p, iAbsLevel, pSeg->iIdx);
+      }
+      *pnRem = 0;
+    }else{
+      /* The incremental merge did not copy all the data from this 
+      ** segment to the upper level. The segment is modified in place
+      ** so that it contains no keys smaller than zTerm/nTerm. */ 
+      const char *zTerm = pSeg->zTerm;
+      int nTerm = pSeg->nTerm;
+      rc = fts3TruncateSegment(p, iAbsLevel, pSeg->iIdx, zTerm, nTerm);
+      nRem++;
+    }
+  }
+
+  if( rc==SQLITE_OK && nRem!=pCsr->nSegment ){
+    rc = fts3RepackSegdirLevel(p, iAbsLevel);
+  }
+
+  *pnRem = nRem;
+  return rc;
+}
+
+/*
+** Store an incr-merge hint in the database.
+*/
+static int fts3IncrmergeHintStore(Fts3Table *p, Blob *pHint){
+  sqlite3_stmt *pReplace = 0;
+  int rc;                         /* Return code */
+
+  rc = fts3SqlStmt(p, SQL_REPLACE_STAT, &pReplace, 0);
+  if( rc==SQLITE_OK ){
+    sqlite3_bind_int(pReplace, 1, FTS_STAT_INCRMERGEHINT);
+    sqlite3_bind_blob(pReplace, 2, pHint->a, pHint->n, SQLITE_STATIC);
+    sqlite3_step(pReplace);
+    rc = sqlite3_reset(pReplace);
+  }
+
+  return rc;
+}
+
+/*
+** Load an incr-merge hint from the database. The incr-merge hint, if one 
+** exists, is stored in the rowid==1 row of the %_stat table.
+**
+** If successful, populate blob *pHint with the value read from the %_stat
+** table and return SQLITE_OK. Otherwise, if an error occurs, return an
+** SQLite error code.
+*/
+static int fts3IncrmergeHintLoad(Fts3Table *p, Blob *pHint){
+  sqlite3_stmt *pSelect = 0;
+  int rc;
+
+  pHint->n = 0;
+  rc = fts3SqlStmt(p, SQL_SELECT_STAT, &pSelect, 0);
+  if( rc==SQLITE_OK ){
+    int rc2;
+    sqlite3_bind_int(pSelect, 1, FTS_STAT_INCRMERGEHINT);
+    if( SQLITE_ROW==sqlite3_step(pSelect) ){
+      const char *aHint = sqlite3_column_blob(pSelect, 0);
+      int nHint = sqlite3_column_bytes(pSelect, 0);
+      if( aHint ){
+        blobGrowBuffer(pHint, nHint, &rc);
+        if( rc==SQLITE_OK ){
+          memcpy(pHint->a, aHint, nHint);
+          pHint->n = nHint;
+        }
+      }
+    }
+    rc2 = sqlite3_reset(pSelect);
+    if( rc==SQLITE_OK ) rc = rc2;
+  }
+
+  return rc;
+}
+
+/*
+** If *pRc is not SQLITE_OK when this function is called, it is a no-op.
+** Otherwise, append an entry to the hint stored in blob *pHint. Each entry
+** consists of two varints, the absolute level number of the input segments 
+** and the number of input segments.
+**
+** If successful, leave *pRc set to SQLITE_OK and return. If an error occurs,
+** set *pRc to an SQLite error code before returning.
+*/
+static void fts3IncrmergeHintPush(
+  Blob *pHint,                    /* Hint blob to append to */
+  i64 iAbsLevel,                  /* First varint to store in hint */
+  int nInput,                     /* Second varint to store in hint */
+  int *pRc                        /* IN/OUT: Error code */
+){
+  blobGrowBuffer(pHint, pHint->n + 2*FTS3_VARINT_MAX, pRc);
+  if( *pRc==SQLITE_OK ){
+    pHint->n += sqlite3Fts3PutVarint(&pHint->a[pHint->n], iAbsLevel);
+    pHint->n += sqlite3Fts3PutVarint(&pHint->a[pHint->n], (i64)nInput);
+  }
+}
+
+/*
+** Read the last entry (most recently pushed) from the hint blob *pHint
+** and then remove the entry. Write the two values read to *piAbsLevel and 
+** *pnInput before returning.
+**
+** If no error occurs, return SQLITE_OK. If the hint blob in *pHint does
+** not contain at least two valid varints, return SQLITE_CORRUPT_VTAB.
+*/
+static int fts3IncrmergeHintPop(Blob *pHint, i64 *piAbsLevel, int *pnInput){
+  const int nHint = pHint->n;
+  int i;
+
+  i = pHint->n-2;
+  while( i>0 && (pHint->a[i-1] & 0x80) ) i--;
+  while( i>0 && (pHint->a[i-1] & 0x80) ) i--;
+
+  pHint->n = i;
+  i += sqlite3Fts3GetVarint(&pHint->a[i], piAbsLevel);
+  i += sqlite3Fts3GetVarint32(&pHint->a[i], pnInput);
+  if( i!=nHint ) return SQLITE_CORRUPT_VTAB;
+
+  return SQLITE_OK;
+}
+
+
+/*
+** Attempt an incremental merge that writes nMerge leaf blocks.
+**
+** Incremental merges happen nMin segments at a time. The two
+** segments to be merged are the nMin oldest segments (the ones with
+** the smallest indexes) in the highest level that contains at least
+** nMin segments. Multiple merges might occur in an attempt to write the 
+** quota of nMerge leaf blocks.
+*/
+int sqlite3Fts3Incrmerge(Fts3Table *p, int nMerge, int nMin){
+  int rc;                         /* Return code */
+  int nRem = nMerge;              /* Number of leaf pages yet to  be written */
+  Fts3MultiSegReader *pCsr;       /* Cursor used to read input data */
+  Fts3SegFilter *pFilter;         /* Filter used with cursor pCsr */
+  IncrmergeWriter *pWriter;       /* Writer object */
+  int nSeg = 0;                   /* Number of input segments */
+  sqlite3_int64 iAbsLevel = 0;    /* Absolute level number to work on */
+  Blob hint = {0, 0, 0};          /* Hint read from %_stat table */
+  int bDirtyHint = 0;             /* True if blob 'hint' has been modified */
+
+  /* Allocate space for the cursor, filter and writer objects */
+  const int nAlloc = sizeof(*pCsr) + sizeof(*pFilter) + sizeof(*pWriter);
+  pWriter = (IncrmergeWriter *)sqlite3_malloc(nAlloc);
+  if( !pWriter ) return SQLITE_NOMEM;
+  pFilter = (Fts3SegFilter *)&pWriter[1];
+  pCsr = (Fts3MultiSegReader *)&pFilter[1];
+
+  rc = fts3IncrmergeHintLoad(p, &hint);
+  while( rc==SQLITE_OK && nRem>0 ){
+    const i64 nMod = FTS3_SEGDIR_MAXLEVEL * p->nIndex;
+    sqlite3_stmt *pFindLevel = 0; /* SQL used to determine iAbsLevel */
+    int bUseHint = 0;             /* True if attempting to append */
+
+    /* Search the %_segdir table for the absolute level with the smallest
+    ** relative level number that contains at least nMin segments, if any.
+    ** If one is found, set iAbsLevel to the absolute level number and
+    ** nSeg to nMin. If no level with at least nMin segments can be found, 
+    ** set nSeg to -1.
+    */
+    rc = fts3SqlStmt(p, SQL_FIND_MERGE_LEVEL, &pFindLevel, 0);
+    sqlite3_bind_int(pFindLevel, 1, nMin);
+    if( sqlite3_step(pFindLevel)==SQLITE_ROW ){
+      iAbsLevel = sqlite3_column_int64(pFindLevel, 0);
+      nSeg = nMin;
+    }else{
+      nSeg = -1;
+    }
+    rc = sqlite3_reset(pFindLevel);
+
+    /* If the hint read from the %_stat table is not empty, check if the
+    ** last entry in it specifies a relative level smaller than or equal
+    ** to the level identified by the block above (if any). If so, this 
+    ** iteration of the loop will work on merging at the hinted level.
+    */
+    if( rc==SQLITE_OK && hint.n ){
+      int nHint = hint.n;
+      sqlite3_int64 iHintAbsLevel = 0;      /* Hint level */
+      int nHintSeg = 0;                     /* Hint number of segments */
+
+      rc = fts3IncrmergeHintPop(&hint, &iHintAbsLevel, &nHintSeg);
+      if( nSeg<0 || (iAbsLevel % nMod) >= (iHintAbsLevel % nMod) ){
+        iAbsLevel = iHintAbsLevel;
+        nSeg = nHintSeg;
+        bUseHint = 1;
+        bDirtyHint = 1;
+      }else{
+        /* This undoes the effect of the HintPop() above - so that no entry
+        ** is removed from the hint blob.  */
+        hint.n = nHint;
+      }
+    }
+
+    /* If nSeg is less that zero, then there is no level with at least
+    ** nMin segments and no hint in the %_stat table. No work to do.
+    ** Exit early in this case.  */
+    if( nSeg<0 ) break;
+
+    /* Open a cursor to iterate through the contents of the oldest nSeg 
+    ** indexes of absolute level iAbsLevel. If this cursor is opened using 
+    ** the 'hint' parameters, it is possible that there are less than nSeg
+    ** segments available in level iAbsLevel. In this case, no work is
+    ** done on iAbsLevel - fall through to the next iteration of the loop 
+    ** to start work on some other level.  */
+    memset(pWriter, 0, nAlloc);
+    pFilter->flags = FTS3_SEGMENT_REQUIRE_POS;
+    if( rc==SQLITE_OK ){
+      rc = fts3IncrmergeCsr(p, iAbsLevel, nSeg, pCsr);
+    }
+    if( SQLITE_OK==rc && pCsr->nSegment==nSeg
+     && SQLITE_OK==(rc = sqlite3Fts3SegReaderStart(p, pCsr, pFilter))
+     && SQLITE_ROW==(rc = sqlite3Fts3SegReaderStep(p, pCsr))
+    ){
+      int iIdx = 0;               /* Largest idx in level (iAbsLevel+1) */
+      rc = fts3IncrmergeOutputIdx(p, iAbsLevel, &iIdx);
+      if( rc==SQLITE_OK ){
+        if( bUseHint && iIdx>0 ){
+          const char *zKey = pCsr->zTerm;
+          int nKey = pCsr->nTerm;
+          rc = fts3IncrmergeLoad(p, iAbsLevel, iIdx-1, zKey, nKey, pWriter);
+        }else{
+          rc = fts3IncrmergeWriter(p, iAbsLevel, iIdx, pCsr, pWriter);
+        }
+      }
+
+      if( rc==SQLITE_OK && pWriter->nLeafEst ){
+        fts3LogMerge(nSeg, iAbsLevel);
+        do {
+          rc = fts3IncrmergeAppend(p, pWriter, pCsr);
+          if( rc==SQLITE_OK ) rc = sqlite3Fts3SegReaderStep(p, pCsr);
+          if( pWriter->nWork>=nRem && rc==SQLITE_ROW ) rc = SQLITE_OK;
+        }while( rc==SQLITE_ROW );
+
+        /* Update or delete the input segments */
+        if( rc==SQLITE_OK ){
+          nRem -= (1 + pWriter->nWork);
+          rc = fts3IncrmergeChomp(p, iAbsLevel, pCsr, &nSeg);
+          if( nSeg!=0 ){
+            bDirtyHint = 1;
+            fts3IncrmergeHintPush(&hint, iAbsLevel, nSeg, &rc);
+          }
+        }
+      }
+
+      fts3IncrmergeRelease(p, pWriter, &rc);
+    }
+
+    sqlite3Fts3SegReaderFinish(pCsr);
+  }
+
+  /* Write the hint values into the %_stat table for the next incr-merger */
+  if( bDirtyHint && rc==SQLITE_OK ){
+    rc = fts3IncrmergeHintStore(p, &hint);
+  }
+
+  sqlite3_free(pWriter);
+  sqlite3_free(hint.a);
+  return rc;
+}
+
+/*
+** Convert the text beginning at *pz into an integer and return
+** its value.  Advance *pz to point to the first character past
+** the integer.
+*/
+static int fts3Getint(const char **pz){
+  const char *z = *pz;
+  int i = 0;
+  while( (*z)>='0' && (*z)<='9' ) i = 10*i + *(z++) - '0';
+  *pz = z;
+  return i;
+}
+
+/*
+** Process statements of the form:
+**
+**    INSERT INTO table(table) VALUES('merge=A,B');
+**
+** A and B are integers that decode to be the number of leaf pages
+** written for the merge, and the minimum number of segments on a level
+** before it will be selected for a merge, respectively.
+*/
+static int fts3DoIncrmerge(
+  Fts3Table *p,                   /* FTS3 table handle */
+  const char *zParam              /* Nul-terminated string containing "A,B" */
+){
+  int rc;
+  int nMin = (FTS3_MERGE_COUNT / 2);
+  int nMerge = 0;
+  const char *z = zParam;
+
+  /* Read the first integer value */
+  nMerge = fts3Getint(&z);
+
+  /* If the first integer value is followed by a ',',  read the second
+  ** integer value. */
+  if( z[0]==',' && z[1]!='\0' ){
+    z++;
+    nMin = fts3Getint(&z);
+  }
+
+  if( z[0]!='\0' || nMin<2 ){
+    rc = SQLITE_ERROR;
+  }else{
+    rc = SQLITE_OK;
+    if( !p->bHasStat ){
+      assert( p->bFts4==0 );
+      sqlite3Fts3CreateStatTable(&rc, p);
+    }
+    if( rc==SQLITE_OK ){
+      rc = sqlite3Fts3Incrmerge(p, nMerge, nMin);
+    }
+    sqlite3Fts3SegmentsClose(p);
+  }
+  return rc;
+}
+
+/*
+** Process statements of the form:
+**
+**    INSERT INTO table(table) VALUES('automerge=X');
+**
+** where X is an integer.  X==0 means to turn automerge off.  X!=0 means
+** turn it on.  The setting is persistent.
+*/
+static int fts3DoAutoincrmerge(
+  Fts3Table *p,                   /* FTS3 table handle */
+  const char *zParam              /* Nul-terminated string containing boolean */
+){
+  int rc = SQLITE_OK;
+  sqlite3_stmt *pStmt = 0;
+  p->bAutoincrmerge = fts3Getint(&zParam)!=0;
+  if( !p->bHasStat ){
+    assert( p->bFts4==0 );
+    sqlite3Fts3CreateStatTable(&rc, p);
+    if( rc ) return rc;
+  }
+  rc = fts3SqlStmt(p, SQL_REPLACE_STAT, &pStmt, 0);
+  if( rc ) return rc;;
+  sqlite3_bind_int(pStmt, 1, FTS_STAT_AUTOINCRMERGE);
+  sqlite3_bind_int(pStmt, 2, p->bAutoincrmerge);
+  sqlite3_step(pStmt);
+  rc = sqlite3_reset(pStmt);
+  return rc;
+}
+
+/*
+** Return a 64-bit checksum for the FTS index entry specified by the
+** arguments to this function.
+*/
+static u64 fts3ChecksumEntry(
+  const char *zTerm,              /* Pointer to buffer containing term */
+  int nTerm,                      /* Size of zTerm in bytes */
+  int iLangid,                    /* Language id for current row */
+  int iIndex,                     /* Index (0..Fts3Table.nIndex-1) */
+  i64 iDocid,                     /* Docid for current row. */
+  int iCol,                       /* Column number */
+  int iPos                        /* Position */
+){
+  int i;
+  u64 ret = (u64)iDocid;
+
+  ret += (ret<<3) + iLangid;
+  ret += (ret<<3) + iIndex;
+  ret += (ret<<3) + iCol;
+  ret += (ret<<3) + iPos;
+  for(i=0; i<nTerm; i++) ret += (ret<<3) + zTerm[i];
+
+  return ret;
+}
+
+/*
+** Return a checksum of all entries in the FTS index that correspond to
+** language id iLangid. The checksum is calculated by XORing the checksums
+** of each individual entry (see fts3ChecksumEntry()) together.
+**
+** If successful, the checksum value is returned and *pRc set to SQLITE_OK.
+** Otherwise, if an error occurs, *pRc is set to an SQLite error code. The
+** return value is undefined in this case.
+*/
+static u64 fts3ChecksumIndex(
+  Fts3Table *p,                   /* FTS3 table handle */
+  int iLangid,                    /* Language id to return cksum for */
+  int iIndex,                     /* Index to cksum (0..p->nIndex-1) */
+  int *pRc                        /* OUT: Return code */
+){
+  Fts3SegFilter filter;
+  Fts3MultiSegReader csr;
+  int rc;
+  u64 cksum = 0;
+
+  assert( *pRc==SQLITE_OK );
+
+  memset(&filter, 0, sizeof(filter));
+  memset(&csr, 0, sizeof(csr));
+  filter.flags =  FTS3_SEGMENT_REQUIRE_POS|FTS3_SEGMENT_IGNORE_EMPTY;
+  filter.flags |= FTS3_SEGMENT_SCAN;
+
+  rc = sqlite3Fts3SegReaderCursor(
+      p, iLangid, iIndex, FTS3_SEGCURSOR_ALL, 0, 0, 0, 1,&csr
+  );
+  if( rc==SQLITE_OK ){
+    rc = sqlite3Fts3SegReaderStart(p, &csr, &filter);
+  }
+
+  if( rc==SQLITE_OK ){
+    while( SQLITE_ROW==(rc = sqlite3Fts3SegReaderStep(p, &csr)) ){
+      char *pCsr = csr.aDoclist;
+      char *pEnd = &pCsr[csr.nDoclist];
+
+      i64 iDocid = 0;
+      i64 iCol = 0;
+      i64 iPos = 0;
+
+      pCsr += sqlite3Fts3GetVarint(pCsr, &iDocid);
+      while( pCsr<pEnd ){
+        i64 iVal = 0;
+        pCsr += sqlite3Fts3GetVarint(pCsr, &iVal);
+        if( pCsr<pEnd ){
+          if( iVal==0 || iVal==1 ){
+            iCol = 0;
+            iPos = 0;
+            if( iVal ){
+              pCsr += sqlite3Fts3GetVarint(pCsr, &iCol);
+            }else{
+              pCsr += sqlite3Fts3GetVarint(pCsr, &iVal);
+              iDocid += iVal;
+            }
+          }else{
+            iPos += (iVal - 2);
+            cksum = cksum ^ fts3ChecksumEntry(
+                csr.zTerm, csr.nTerm, iLangid, iIndex, iDocid,
+                (int)iCol, (int)iPos
+            );
+          }
+        }
+      }
+    }
+  }
+  sqlite3Fts3SegReaderFinish(&csr);
+
+  *pRc = rc;
+  return cksum;
+}
+
+/*
+** Check if the contents of the FTS index match the current contents of the
+** content table. If no error occurs and the contents do match, set *pbOk
+** to true and return SQLITE_OK. Or if the contents do not match, set *pbOk
+** to false before returning.
+**
+** If an error occurs (e.g. an OOM or IO error), return an SQLite error 
+** code. The final value of *pbOk is undefined in this case.
+*/
+static int fts3IntegrityCheck(Fts3Table *p, int *pbOk){
+  int rc = SQLITE_OK;             /* Return code */
+  u64 cksum1 = 0;                 /* Checksum based on FTS index contents */
+  u64 cksum2 = 0;                 /* Checksum based on %_content contents */
+  sqlite3_stmt *pAllLangid = 0;   /* Statement to return all language-ids */
+
+  /* This block calculates the checksum according to the FTS index. */
+  rc = fts3SqlStmt(p, SQL_SELECT_ALL_LANGID, &pAllLangid, 0);
+  if( rc==SQLITE_OK ){
+    int rc2;
+    sqlite3_bind_int(pAllLangid, 1, p->nIndex);
+    while( rc==SQLITE_OK && sqlite3_step(pAllLangid)==SQLITE_ROW ){
+      int iLangid = sqlite3_column_int(pAllLangid, 0);
+      int i;
+      for(i=0; i<p->nIndex; i++){
+        cksum1 = cksum1 ^ fts3ChecksumIndex(p, iLangid, i, &rc);
+      }
+    }
+    rc2 = sqlite3_reset(pAllLangid);
+    if( rc==SQLITE_OK ) rc = rc2;
+  }
+
+  /* This block calculates the checksum according to the %_content table */
+  rc = fts3SqlStmt(p, SQL_SELECT_ALL_LANGID, &pAllLangid, 0);
+  if( rc==SQLITE_OK ){
+    sqlite3_tokenizer_module const *pModule = p->pTokenizer->pModule;
+    sqlite3_stmt *pStmt = 0;
+    char *zSql;
+   
+    zSql = sqlite3_mprintf("SELECT %s" , p->zReadExprlist);
+    if( !zSql ){
+      rc = SQLITE_NOMEM;
+    }else{
+      rc = sqlite3_prepare_v2(p->db, zSql, -1, &pStmt, 0);
+      sqlite3_free(zSql);
+    }
+
+    while( rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pStmt) ){
+      i64 iDocid = sqlite3_column_int64(pStmt, 0);
+      int iLang = langidFromSelect(p, pStmt);
+      int iCol;
+
+      for(iCol=0; rc==SQLITE_OK && iCol<p->nColumn; iCol++){
+        const char *zText = (const char *)sqlite3_column_text(pStmt, iCol+1);
+        int nText = sqlite3_column_bytes(pStmt, iCol+1);
+        sqlite3_tokenizer_cursor *pT = 0;
+
+        rc = sqlite3Fts3OpenTokenizer(p->pTokenizer, iLang, zText, nText, &pT);
+        while( rc==SQLITE_OK ){
+          char const *zToken;       /* Buffer containing token */
+          int nToken = 0;           /* Number of bytes in token */
+          int iDum1 = 0, iDum2 = 0; /* Dummy variables */
+          int iPos = 0;             /* Position of token in zText */
+
+          rc = pModule->xNext(pT, &zToken, &nToken, &iDum1, &iDum2, &iPos);
+          if( rc==SQLITE_OK ){
+            int i;
+            cksum2 = cksum2 ^ fts3ChecksumEntry(
+                zToken, nToken, iLang, 0, iDocid, iCol, iPos
+            );
+            for(i=1; i<p->nIndex; i++){
+              if( p->aIndex[i].nPrefix<=nToken ){
+                cksum2 = cksum2 ^ fts3ChecksumEntry(
+                  zToken, p->aIndex[i].nPrefix, iLang, i, iDocid, iCol, iPos
+                );
+              }
+            }
+          }
+        }
+        if( pT ) pModule->xClose(pT);
+        if( rc==SQLITE_DONE ) rc = SQLITE_OK;
+      }
+    }
+
+    sqlite3_finalize(pStmt);
+  }
+
+  *pbOk = (cksum1==cksum2);
+  return rc;
+}
+
+/*
+** Run the integrity-check. If no error occurs and the current contents of
+** the FTS index are correct, return SQLITE_OK. Or, if the contents of the
+** FTS index are incorrect, return SQLITE_CORRUPT_VTAB.
+**
+** Or, if an error (e.g. an OOM or IO error) occurs, return an SQLite 
+** error code.
+**
+** The integrity-check works as follows. For each token and indexed token
+** prefix in the document set, a 64-bit checksum is calculated (by code
+** in fts3ChecksumEntry()) based on the following:
+**
+**     + The index number (0 for the main index, 1 for the first prefix
+**       index etc.),
+**     + The token (or token prefix) text itself, 
+**     + The language-id of the row it appears in,
+**     + The docid of the row it appears in,
+**     + The column it appears in, and
+**     + The tokens position within that column.
+**
+** The checksums for all entries in the index are XORed together to create
+** a single checksum for the entire index.
+**
+** The integrity-check code calculates the same checksum in two ways:
+**
+**     1. By scanning the contents of the FTS index, and 
+**     2. By scanning and tokenizing the content table.
+**
+** If the two checksums are identical, the integrity-check is deemed to have
+** passed.
+*/
+static int fts3DoIntegrityCheck(
+  Fts3Table *p                    /* FTS3 table handle */
+){
+  int rc;
+  int bOk = 0;
+  rc = fts3IntegrityCheck(p, &bOk);
+  if( rc==SQLITE_OK && bOk==0 ) rc = SQLITE_CORRUPT_VTAB;
+  return rc;
+}
+
+/*
 ** Handle a 'special' INSERT of the form:
 **
 **   "INSERT INTO tbl(tbl) VALUES(<expr>)"
@@ -2928,6 +5026,14 @@ static int fts3SpecialInsert(Fts3Table *p, sqlite3_value *pVal){
     return SQLITE_NOMEM;
   }else if( nVal==8 && 0==sqlite3_strnicmp(zVal, "optimize", 8) ){
     rc = fts3DoOptimize(p, 0);
+  }else if( nVal==7 && 0==sqlite3_strnicmp(zVal, "rebuild", 7) ){
+    rc = fts3DoRebuild(p);
+  }else if( nVal==15 && 0==sqlite3_strnicmp(zVal, "integrity-check", 15) ){
+    rc = fts3DoIntegrityCheck(p);
+  }else if( nVal>6 && 0==sqlite3_strnicmp(zVal, "merge=", 6) ){
+    rc = fts3DoIncrmerge(p, &zVal[6]);
+  }else if( nVal>10 && 0==sqlite3_strnicmp(zVal, "automerge=", 10) ){
+    rc = fts3DoAutoincrmerge(p, &zVal[10]);
 #ifdef SQLITE_TEST
   }else if( nVal>9 && 0==sqlite3_strnicmp(zVal, "nodesize=", 9) ){
     p->nNodeSize = atoi(&zVal[9]);
@@ -2943,6 +5049,7 @@ static int fts3SpecialInsert(Fts3Table *p, sqlite3_value *pVal){
   return rc;
 }
 
+#ifndef SQLITE_DISABLE_FTS4_DEFERRED
 /*
 ** Delete all cached deferred doclists. Deferred doclists are cached
 ** (allocated) by the sqlite3Fts3CacheDeferredDoclists() function.
@@ -2996,18 +5103,18 @@ int sqlite3Fts3CacheDeferredDoclists(Fts3Cursor *pCsr){
       const char *zText = (const char *)sqlite3_column_text(pCsr->pStmt, i+1);
       sqlite3_tokenizer_cursor *pTC = 0;
   
-      rc = pModule->xOpen(pT, zText, -1, &pTC);
+      rc = sqlite3Fts3OpenTokenizer(pT, pCsr->iLangid, zText, -1, &pTC);
       while( rc==SQLITE_OK ){
         char const *zToken;       /* Buffer containing token */
-        int nToken;               /* Number of bytes in token */
-        int iDum1, iDum2;         /* Dummy variables */
-        int iPos;                 /* Position of token in zText */
+        int nToken = 0;           /* Number of bytes in token */
+        int iDum1 = 0, iDum2 = 0; /* Dummy variables */
+        int iPos = 0;             /* Position of token in zText */
   
-        pTC->pTokenizer = pT;
         rc = pModule->xNext(pTC, &zToken, &nToken, &iDum1, &iDum2, &iPos);
         for(pDef=pCsr->pDeferred; pDef && rc==SQLITE_OK; pDef=pDef->pNext){
           Fts3PhraseToken *pPT = pDef->pToken;
           if( (pDef->iCol>=p->nColumn || pDef->iCol==i)
+           && (pPT->bFirst==0 || iPos==0)
            && (pPT->n==nToken || (pPT->isPrefix && pPT->n<nToken))
            && (0==memcmp(zToken, pPT->z, pPT->n))
           ){
@@ -3080,6 +5187,7 @@ int sqlite3Fts3DeferToken(
 
   return SQLITE_OK;
 }
+#endif
 
 /*
 ** SQLite value pRowid contains the rowid of a row that may or may not be
@@ -3089,26 +5197,32 @@ int sqlite3Fts3DeferToken(
 static int fts3DeleteByRowid(
   Fts3Table *p, 
   sqlite3_value *pRowid, 
-  int *pnDoc,
+  int *pnChng,                    /* IN/OUT: Decrement if row is deleted */
   u32 *aSzDel
 ){
-  int isEmpty = 0;
-  int rc = fts3IsEmpty(p, pRowid, &isEmpty);
-  if( rc==SQLITE_OK ){
-    if( isEmpty ){
-      /* Deleting this row means the whole table is empty. In this case
-      ** delete the contents of all three tables and throw away any
-      ** data in the pendingTerms hash table.  */
-      rc = fts3DeleteAll(p);
-      *pnDoc = *pnDoc - 1;
-    }else{
-      sqlite3_int64 iRemove = sqlite3_value_int64(pRowid);
-      rc = fts3PendingTermsDocid(p, iRemove);
-      fts3DeleteTerms(&rc, p, pRowid, aSzDel);
-      fts3SqlExec(&rc, p, SQL_DELETE_CONTENT, &pRowid);
-      if( sqlite3_changes(p->db) ) *pnDoc = *pnDoc - 1;
-      if( p->bHasDocsize ){
-        fts3SqlExec(&rc, p, SQL_DELETE_DOCSIZE, &pRowid);
+  int rc = SQLITE_OK;             /* Return code */
+  int bFound = 0;                 /* True if *pRowid really is in the table */
+
+  fts3DeleteTerms(&rc, p, pRowid, aSzDel, &bFound);
+  if( bFound && rc==SQLITE_OK ){
+    int isEmpty = 0;              /* Deleting *pRowid leaves the table empty */
+    rc = fts3IsEmpty(p, pRowid, &isEmpty);
+    if( rc==SQLITE_OK ){
+      if( isEmpty ){
+        /* Deleting this row means the whole table is empty. In this case
+        ** delete the contents of all three tables and throw away any
+        ** data in the pendingTerms hash table.  */
+        rc = fts3DeleteAll(p, 1);
+        *pnChng = 0;
+        memset(aSzDel, 0, sizeof(u32) * (p->nColumn+1) * 2);
+      }else{
+        *pnChng = *pnChng - 1;
+        if( p->zContentTbl==0 ){
+          fts3SqlExec(&rc, p, SQL_DELETE_CONTENT, &pRowid);
+        }
+        if( p->bHasDocsize ){
+          fts3SqlExec(&rc, p, SQL_DELETE_DOCSIZE, &pRowid);
+        }
       }
     }
   }
@@ -3118,7 +5232,16 @@ static int fts3DeleteByRowid(
 
 /*
 ** This function does the work for the xUpdate method of FTS3 virtual
-** tables.
+** tables. The schema of the virtual table being:
+**
+**     CREATE TABLE <table name>( 
+**       <user columns>,
+**       <table name> HIDDEN, 
+**       docid HIDDEN, 
+**       <langid> HIDDEN
+**     );
+**
+** 
 */
 int sqlite3Fts3UpdateMethod(
   sqlite3_vtab *pVtab,            /* FTS3 vtab object */
@@ -3129,13 +5252,16 @@ int sqlite3Fts3UpdateMethod(
   Fts3Table *p = (Fts3Table *)pVtab;
   int rc = SQLITE_OK;             /* Return Code */
   int isRemove = 0;               /* True for an UPDATE or DELETE */
-  sqlite3_int64 iRemove = 0;      /* Rowid removed by UPDATE or DELETE */
   u32 *aSzIns = 0;                /* Sizes of inserted documents */
-  u32 *aSzDel;                    /* Sizes of deleted documents */
+  u32 *aSzDel = 0;                /* Sizes of deleted documents */
   int nChng = 0;                  /* Net change in number of documents */
   int bInsertDone = 0;
 
   assert( p->pSegments==0 );
+  assert( 
+      nArg==1                     /* DELETE operations */
+   || nArg==(2 + p->nColumn + 3)  /* INSERT or UPDATE operations */
+  );
 
   /* Check for a "special" INSERT operation. One of the form:
   **
@@ -3149,14 +5275,19 @@ int sqlite3Fts3UpdateMethod(
     goto update_out;
   }
 
+  if( nArg>1 && sqlite3_value_int(apVal[2 + p->nColumn + 2])<0 ){
+    rc = SQLITE_CONSTRAINT;
+    goto update_out;
+  }
+
   /* Allocate space to hold the change in document sizes */
-  aSzIns = sqlite3_malloc( sizeof(aSzIns[0])*(p->nColumn+1)*2 );
-  if( aSzIns==0 ){
+  aSzDel = sqlite3_malloc( sizeof(aSzDel[0])*(p->nColumn+1)*2 );
+  if( aSzDel==0 ){
     rc = SQLITE_NOMEM;
     goto update_out;
   }
-  aSzDel = &aSzIns[p->nColumn+1];
-  memset(aSzIns, 0, sizeof(aSzIns[0])*(p->nColumn+1)*2);
+  aSzIns = &aSzDel[p->nColumn+1];
+  memset(aSzDel, 0, sizeof(aSzDel[0])*(p->nColumn+1)*2);
 
   /* If this is an INSERT operation, or an UPDATE that modifies the rowid
   ** value, then this operation requires constraint handling.
@@ -3167,7 +5298,7 @@ int sqlite3Fts3UpdateMethod(
   ** detect the conflict and return SQLITE_CONSTRAINT before beginning to
   ** modify the database file.
   */
-  if( nArg>1 ){
+  if( nArg>1 && p->zContentTbl==0 ){
     /* Find the value object that holds the new rowid value. */
     sqlite3_value *pNewRowid = apVal[3+p->nColumn];
     if( sqlite3_value_type(pNewRowid)==SQLITE_NULL ){
@@ -3212,20 +5343,23 @@ int sqlite3Fts3UpdateMethod(
     assert( sqlite3_value_type(apVal[0])==SQLITE_INTEGER );
     rc = fts3DeleteByRowid(p, apVal[0], &nChng, aSzDel);
     isRemove = 1;
-    iRemove = sqlite3_value_int64(apVal[0]);
   }
   
   /* If this is an INSERT or UPDATE operation, insert the new record. */
   if( nArg>1 && rc==SQLITE_OK ){
+    int iLangid = sqlite3_value_int(apVal[2 + p->nColumn + 2]);
     if( bInsertDone==0 ){
       rc = fts3InsertData(p, apVal, pRowid);
-      if( rc==SQLITE_CONSTRAINT ) rc = SQLITE_CORRUPT_VTAB;
+      if( rc==SQLITE_CONSTRAINT && p->zContentTbl==0 ){
+        rc = FTS_CORRUPT_VTAB;
+      }
     }
-    if( rc==SQLITE_OK && (!isRemove || *pRowid!=iRemove) ){
-      rc = fts3PendingTermsDocid(p, *pRowid);
+    if( rc==SQLITE_OK && (!isRemove || *pRowid!=p->iPrevDocid ) ){
+      rc = fts3PendingTermsDocid(p, iLangid, *pRowid);
     }
     if( rc==SQLITE_OK ){
-      rc = fts3InsertTerms(p, apVal, aSzIns);
+      assert( p->iPrevDocid==*pRowid );
+      rc = fts3InsertTerms(p, iLangid, apVal, aSzIns);
     }
     if( p->bHasDocsize ){
       fts3InsertDocsize(&rc, p, aSzIns);
@@ -3233,12 +5367,12 @@ int sqlite3Fts3UpdateMethod(
     nChng++;
   }
 
-  if( p->bHasStat ){
+  if( p->bFts4 ){
     fts3UpdateDocTotals(&rc, p, aSzIns, aSzDel, nChng);
   }
 
  update_out:
-  sqlite3_free(aSzIns);
+  sqlite3_free(aSzDel);
   sqlite3Fts3SegmentsClose(p);
   return rc;
 }