Bug#42643: InnoDB does not support replication of TRUNCATE TABLE

The problem was that TRUNCATE TABLE didn't take a exclusive
lock on a table if it resorted to truncating via delete of
all rows in the table. Specifically for InnoDB tables, this
could break proper isolation as InnoDB ends up aborting some
granted locks when truncating a table.

The solution is to take a exclusive metadata lock before
TRUNCATE TABLE can proceed. This guarantees that no other
transaction is using the table.

Incompatible change: Truncate via delete no longer fails
if sql_safe_updates is activated (this was a undocumented
side effect).

1 files changed, 15 insertions, 299 deletions

diff --git a/sql/sql_delete.cc b/sql/sql_delete.cc
index 10bdb8a22a6..730cb711a05 100644
--- a/sql/sql_delete.cc
+++ b/sql/sql_delete.cc
@@ -14,7 +14,7 @@
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */
 
 /*
-  Delete of records and truncate of tables.
+  Delete of records tables.
 
   Multi-table deletes were introduced by Monty and Sinisa
 */
@@ -48,8 +48,7 @@
 */
 
 bool mysql_delete(THD *thd, TABLE_LIST *table_list, COND *conds,
-                  SQL_LIST *order, ha_rows limit, ulonglong options,
-                  bool reset_auto_increment)
+                  SQL_LIST *order, ha_rows limit, ulonglong options)
 {
   bool          will_batch;
   int		error, loc_error;
@@ -60,17 +59,11 @@ bool mysql_delete(THD *thd, TABLE_LIST *table_list, COND *conds,
   bool		transactional_table, safe_update, const_cond;
   bool          const_cond_result;
   ha_rows	deleted= 0;
-  bool          triggers_applicable;
   uint usable_index= MAX_KEY;
   SELECT_LEX   *select_lex= &thd->lex->select_lex;
   THD::killed_state killed_status= THD::NOT_KILLED;
+  THD::enum_binlog_query_type query_type= THD::ROW_QUERY_TYPE;
   DBUG_ENTER("mysql_delete");
-  bool save_binlog_row_based;
-
-  THD::enum_binlog_query_type query_type=
-    thd->lex->sql_command == SQLCOM_TRUNCATE ?
-    THD::STMT_QUERY_TYPE :
-    THD::ROW_QUERY_TYPE;
 
   if (open_and_lock_tables(thd, table_list, TRUE, 0))
     DBUG_RETURN(TRUE);
@@ -130,25 +123,20 @@ bool mysql_delete(THD *thd, TABLE_LIST *table_list, COND *conds,
     any side-effects (because of triggers), so we can use optimized
     handler::delete_all_rows() method.
 
-    We implement fast TRUNCATE for InnoDB even if triggers are
-    present.  TRUNCATE ignores triggers.
-
     We can use delete_all_rows() if and only if:
     - We allow new functions (not using option --skip-new), and are
       not in safe mode (not using option --safe-mode)
     - There is no limit clause
     - The condition is constant
     - If there is a condition, then it it produces a non-zero value
-    - If the current command is DELETE FROM with no where clause
-      (i.e., not TRUNCATE) then:
-      - We should not be binlogging this statement row-based, and
+    - If the current command is DELETE FROM with no where clause, then:
+      - We should not be binlogging this statement in row-based, and
       - there should be no delete triggers associated with the table.
   */
   if (!using_limit && const_cond_result &&
       !(specialflag & (SPECIAL_NO_NEW_FUNC | SPECIAL_SAFE_MODE)) &&
-      (thd->lex->sql_command == SQLCOM_TRUNCATE ||
        (!thd->is_current_stmt_binlog_format_row() &&
-        !(table->triggers && table->triggers->has_delete_triggers()))))
+        !(table->triggers && table->triggers->has_delete_triggers())))
   {
     /* Update the table->file->stats.records number */
     table->file->info(HA_STATUS_VARIABLE | HA_STATUS_NO_LOCK);
@@ -161,16 +149,14 @@ bool mysql_delete(THD *thd, TABLE_LIST *table_list, COND *conds,
         query in row format, so we have to log it in statement format.
       */
       query_type= THD::STMT_QUERY_TYPE;
-      error= -1;				// ok
+      error= -1;
       deleted= maybe_deleted;
-      save_binlog_row_based= thd->is_current_stmt_binlog_format_row();
       goto cleanup;
     }
     if (error != HA_ERR_WRONG_COMMAND)
     {
       table->file->print_error(error,MYF(0));
       error=0;
-      save_binlog_row_based= thd->is_current_stmt_binlog_format_row();
       goto cleanup;
     }
     /* Handler didn't support fast delete; Delete rows one by one */
@@ -213,11 +199,6 @@ bool mysql_delete(THD *thd, TABLE_LIST *table_list, COND *conds,
     if (thd->is_error())
       DBUG_RETURN(TRUE);
     my_ok(thd, 0);
-    /*
-      We don't need to call reset_auto_increment in this case, because
-      mysql_truncate always gives a NULL conds argument, hence we never
-      get here.
-    */
     DBUG_RETURN(0);				// Nothing to delete
   }
 
@@ -287,12 +268,7 @@ bool mysql_delete(THD *thd, TABLE_LIST *table_list, COND *conds,
   init_ftfuncs(thd, select_lex, 1);
   thd_proc_info(thd, "updating");
 
-  /* NOTE: TRUNCATE must not invoke triggers. */
-
-  triggers_applicable= table->triggers &&
-                       thd->lex->sql_command != SQLCOM_TRUNCATE;
-
-  if (triggers_applicable &&
+  if (table->triggers &&
       table->triggers->has_triggers(TRG_EVENT_DELETE,
                                     TRG_ACTION_AFTER))
   {
@@ -310,11 +286,6 @@ bool mysql_delete(THD *thd, TABLE_LIST *table_list, COND *conds,
 
   table->mark_columns_needed_for_delete();
 
-  save_binlog_row_based= thd->is_current_stmt_binlog_format_row();
-  if (thd->lex->sql_command == SQLCOM_TRUNCATE &&
-      thd->is_current_stmt_binlog_format_row())
-    thd->clear_current_stmt_binlog_format_row();
-
   while (!(error=info.read_record(&info)) && !thd->killed &&
 	 ! thd->is_error())
   {
@@ -322,7 +293,7 @@ bool mysql_delete(THD *thd, TABLE_LIST *table_list, COND *conds,
     if (!(select && select->skip_record())&& ! thd->is_error() )
     {
 
-      if (triggers_applicable &&
+      if (table->triggers &&
           table->triggers->process_triggers(thd, TRG_EVENT_DELETE,
                                             TRG_ACTION_BEFORE, FALSE))
       {
@@ -333,7 +304,7 @@ bool mysql_delete(THD *thd, TABLE_LIST *table_list, COND *conds,
       if (!(error= table->file->ha_delete_row(table->record[0])))
       {
 	deleted++;
-        if (triggers_applicable &&
+        if (table->triggers &&
             table->triggers->process_triggers(thd, TRG_EVENT_DELETE,
                                               TRG_ACTION_AFTER, FALSE))
         {
@@ -378,21 +349,6 @@ bool mysql_delete(THD *thd, TABLE_LIST *table_list, COND *conds,
   if (options & OPTION_QUICK)
     (void) table->file->extra(HA_EXTRA_NORMAL);
 
-  if (reset_auto_increment && (error < 0))
-  {
-    /*
-      We're really doing a truncate and need to reset the table's
-      auto-increment counter.
-    */
-    int error2= table->file->ha_reset_auto_increment(0);
-
-    if (error2 && (error2 != HA_ERR_WRONG_COMMAND))
-    {
-      table->file->print_error(error2, MYF(0));
-      error= 1;
-    }
-  }
-
 cleanup:
   /*
     Invalidate the table in the query cache if something changed. This must
@@ -413,34 +369,24 @@ cleanup:
   /* See similar binlogging code in sql_update.cc, for comments */
   if ((error < 0) || thd->transaction.stmt.modified_non_trans_table)
   {
-    if (mysql_bin_log.is_open() &&
-        !(thd->lex->sql_command == SQLCOM_TRUNCATE &&
-          thd->is_current_stmt_binlog_format_row() &&
-          find_temporary_table(thd, table_list)))
+    if (mysql_bin_log.is_open())
     {
-      bool const is_trans=
-        thd->lex->sql_command == SQLCOM_TRUNCATE ?
-        FALSE :
-        transactional_table;
-
       int errcode= 0;
       if (error < 0)
         thd->clear_error();
       else
         errcode= query_error_code(thd, killed_status == THD::NOT_KILLED);
-      
+
       /*
         [binlog]: If 'handler::delete_all_rows()' was called and the
         storage engine does not inject the rows itself, we replicate
         statement-based; otherwise, 'ha_delete_row()' was used to
         delete specific rows which we might log row-based.
-
-        Note that TRUNCATE TABLE is not transactional and should
-        therefore be treated as a DDL.
       */
       int log_result= thd->binlog_query(query_type,
                                         thd->query(), thd->query_length(),
-                                        is_trans, FALSE, FALSE, errcode);
+                                        transactional_table, FALSE, FALSE,
+                                        errcode);
 
       if (log_result)
       {
@@ -448,18 +394,12 @@ cleanup:
       }
     }
   }
-  if (save_binlog_row_based)
-    thd->set_current_stmt_binlog_format_row();
   DBUG_ASSERT(transactional_table || !deleted || thd->transaction.stmt.modified_non_trans_table);
   free_underlaid_joins(thd, select_lex);
   if (error < 0 || 
       (thd->lex->ignore && !thd->is_error() && !thd->is_fatal_error))
   {
-    /*
-      If a TRUNCATE TABLE was issued, the number of rows should be reported as
-      zero since the exact number is unknown.
-    */
-    my_ok(thd, reset_auto_increment ? 0 : deleted);
+    my_ok(thd, deleted);
     DBUG_PRINT("info",("%ld records deleted",(long) deleted));
   }
   DBUG_RETURN(error >= 0 || thd->is_error());
@@ -1061,227 +1001,3 @@ bool multi_delete::send_eof()
   return 0;
 }
 
-
-/***************************************************************************
-  TRUNCATE TABLE
-****************************************************************************/
-
-/*
-  Row-by-row truncation if the engine does not support table recreation.
-  Probably a InnoDB table.
-*/
-
-static bool mysql_truncate_by_delete(THD *thd, TABLE_LIST *table_list)
-{
-  bool error;
-  DBUG_ENTER("mysql_truncate_by_delete");
-  table_list->lock_type= TL_WRITE;
-  table_list->mdl_request.set_type(MDL_SHARED_WRITE);
-  mysql_init_select(thd->lex);
-  /* Delete all rows from table */
-  error= mysql_delete(thd, table_list, NULL, NULL, HA_POS_ERROR, LL(0), TRUE);
-  /*
-    All effects of a TRUNCATE TABLE operation are rolled back if a row by row
-    deletion fails. Otherwise, operation is automatically committed at the end.
-  */
-  if (error)
-  {
-    DBUG_ASSERT(thd->stmt_da->is_error());
-    trans_rollback_stmt(thd);
-    trans_rollback(thd);
-  }
-  DBUG_RETURN(error);
-}
-
-
-/*
-  Optimize delete of all rows by doing a full generate of the table
-  This will work even if the .ISM and .ISD tables are destroyed
-
-  dont_send_ok should be set if:
-  - We should always wants to generate the table (even if the table type
-    normally can't safely do this.
-  - We don't want an ok to be sent to the end user.
-  - We don't want to log the truncate command
-  - If we want to keep exclusive metadata lock on the table (obtained by
-    caller) on exit without errors.
-*/
-
-bool mysql_truncate(THD *thd, TABLE_LIST *table_list, bool dont_send_ok)
-{
-  HA_CREATE_INFO create_info;
-  char path[FN_REFLEN + 1];
-  TABLE *table;
-  bool error= TRUE;
-  uint path_length;
-  /*
-    Is set if we're under LOCK TABLES, and used
-    to downgrade the exclusive lock after the
-    table was truncated.
-  */
-  MDL_ticket *mdl_ticket= NULL;
-  bool has_mdl_lock= FALSE;
-  bool is_temporary_table= false;
-  DBUG_ENTER("mysql_truncate");
-
-  bzero((char*) &create_info,sizeof(create_info));
-
-  /* Remove tables from the HANDLER's hash. */
-  mysql_ha_rm_tables(thd, table_list);
-
-  /* If it is a temporary table, close and regenerate it */
-  if (!dont_send_ok && (table= find_temporary_table(thd, table_list)))
-  {
-    is_temporary_table= true;
-    handlerton *table_type= table->s->db_type();
-    TABLE_SHARE *share= table->s;
-    /* Note that a temporary table cannot be partitioned */
-    if (!ha_check_storage_engine_flag(table_type, HTON_CAN_RECREATE))
-      goto trunc_by_del;
-
-    table->file->info(HA_STATUS_AUTO | HA_STATUS_NO_LOCK);
-
-    close_temporary_table(thd, table, 0, 0);    // Don't free share
-    ha_create_table(thd, share->normalized_path.str,
-                    share->db.str, share->table_name.str, &create_info, 1);
-    // We don't need to call invalidate() because this table is not in cache
-    if ((error= (int) !(open_temporary_table(thd, share->path.str,
-                                             share->db.str,
-					     share->table_name.str, 1))))
-      (void) rm_temporary_table(table_type, path);
-    else
-      thd->thread_specific_used= TRUE;
-    
-    free_table_share(share);
-    my_free((char*) table,MYF(0));
-    /*
-      If we return here we will not have logged the truncation to the bin log
-      and we will not my_ok() to the client.
-    */
-    goto end;
-  }
-
-  path_length= build_table_filename(path, sizeof(path) - 1, table_list->db,
-                                    table_list->table_name, reg_ext, 0);
-
-  if (!dont_send_ok)
-  {
-    enum legacy_db_type table_type;
-    /*
-      FIXME: Code of TRUNCATE breaks the meta-data
-      locking protocol since it tries to find out the table storage
-      engine and therefore accesses table in some way without holding
-      any kind of meta-data lock.
-    */
-    mysql_frm_type(thd, path, &table_type);
-    if (table_type == DB_TYPE_UNKNOWN)
-    {
-      my_error(ER_NO_SUCH_TABLE, MYF(0),
-               table_list->db, table_list->table_name);
-      DBUG_RETURN(TRUE);
-    }
-#ifdef WITH_PARTITION_STORAGE_ENGINE
-    /*
-      TODO: Add support for TRUNCATE PARTITION for NDB and other engines
-      supporting native partitioning
-    */
-    if (table_type != DB_TYPE_PARTITION_DB &&
-        thd->lex->alter_info.flags & ALTER_ADMIN_PARTITION)
-    {
-      my_error(ER_PARTITION_MGMT_ON_NONPARTITIONED, MYF(0));
-      DBUG_RETURN(TRUE);
-    }
-#endif
-    if (!ha_check_storage_engine_flag(ha_resolve_by_legacy_type(thd,
-                                                                table_type),
-                                      HTON_CAN_RECREATE) ||
-        thd->lex->alter_info.flags & ALTER_ADMIN_PARTITION)
-      goto trunc_by_del;
-
-
-    if (thd->locked_tables_mode)
-    {
-      if (!(table= find_table_for_mdl_upgrade(thd->open_tables, table_list->db,
-                                              table_list->table_name, FALSE)))
-        DBUG_RETURN(TRUE);
-      mdl_ticket= table->mdl_ticket;
-      if (wait_while_table_is_used(thd, table, HA_EXTRA_FORCE_REOPEN))
-        goto end;
-      close_all_tables_for_name(thd, table->s, FALSE);
-    }
-    else
-    {
-      MDL_request mdl_global_request, mdl_request;
-      MDL_request_list mdl_requests;
-      /*
-        Even though we could use the previous execution branch
-        here just as well, we must not try to open the table: 
-        MySQL manual documents that TRUNCATE can be used to 
-        repair a damaged table, i.e. a table that can not be
-        fully "opened". In particular MySQL manual says:
-
-        As long as the table format file tbl_name.frm  is valid,
-        the table can be re-created as an empty table with TRUNCATE
-        TABLE, even if the data or index files have become corrupted.
-      */
-
-      mdl_global_request.init(MDL_key::GLOBAL, "", "", MDL_INTENTION_EXCLUSIVE);
-      mdl_request.init(MDL_key::TABLE, table_list->db, table_list->table_name,
-                       MDL_EXCLUSIVE);
-      mdl_requests.push_front(&mdl_request);
-      mdl_requests.push_front(&mdl_global_request);
-
-      if (thd->mdl_context.acquire_locks(&mdl_requests,
-                                         thd->variables.lock_wait_timeout))
-        DBUG_RETURN(TRUE);
-
-      has_mdl_lock= TRUE;
-      mysql_mutex_lock(&LOCK_open);
-      tdc_remove_table(thd, TDC_RT_REMOVE_ALL, table_list->db,
-                       table_list->table_name);
-      mysql_mutex_unlock(&LOCK_open);
-    }
-  }
-
-  /*
-    Remove the .frm extension AIX 5.2 64-bit compiler bug (BUG#16155): this
-    crashes, replacement works.  *(path + path_length - reg_ext_length)=
-     '\0';
-  */
-  path[path_length - reg_ext_length] = 0;
-  mysql_mutex_lock(&LOCK_open);
-  error= ha_create_table(thd, path, table_list->db, table_list->table_name,
-                         &create_info, 1);
-  mysql_mutex_unlock(&LOCK_open);
-  query_cache_invalidate3(thd, table_list, 0);
-
-end:
-  if (!dont_send_ok)
-  {
-    if (thd->locked_tables_mode && thd->locked_tables_list.reopen_tables(thd))
-      thd->locked_tables_list.unlink_all_closed_tables(thd, NULL, 0);
-    /*
-      Even if we failed to reopen some tables,
-      the operation itself succeeded, write the binlog.
-    */
-    if (!error)
-    {
-      /* In RBR, the statement is not binlogged if the table is temporary. */
-      if (!is_temporary_table || !thd->is_current_stmt_binlog_format_row())
-        error= write_bin_log(thd, TRUE, thd->query(), thd->query_length());
-      if (!error)
-        my_ok(thd);             // This should return record count
-    }
-    if (has_mdl_lock)
-      thd->mdl_context.release_transactional_locks();
-    if (mdl_ticket)
-      mdl_ticket->downgrade_exclusive_lock(MDL_SHARED_NO_READ_WRITE);
-  }
-
-  DBUG_PRINT("exit", ("error: %d", error));
-  DBUG_RETURN(error);
-
-trunc_by_del:
-  error= mysql_truncate_by_delete(thd, table_list);
-  DBUG_RETURN(error);
-}