Bug #49756 Rows_examined is always 0 in the slow query log for

update statements
      
Only SELECT statements report any examined rows in the slow
log. Slow UPDATE, DELETE and INSERT statements report 0 rows
examined, unless the statement has a condition including a
SELECT substatement.
      
This patch adds counting of examined rows for the UPDATE and
DELETE statements. An INSERT ... VALUES statement will still 
not report any rows as examined.



sql/sql_class.h:
  Added more docs for THD::examined_row_count.
sql/sql_delete.cc:
  Add incrementing thd->examined_row_count.
sql/sql_update.cc:
  Add incrementing thd->examined_row_count.

3 files changed, 14 insertions, 2 deletions

diff --git a/sql/sql_class.h b/sql/sql_class.h
index 4d0552c5b9d..bd3cf8bc401 100644
--- a/sql/sql_class.h
+++ b/sql/sql_class.h
@@ -1716,8 +1716,15 @@ public:
   */
   ha_rows    sent_row_count;
 
-  /*
-    number of rows we read, sent or not, including in create_sort_index()
+  /**
+    Number of rows read and/or evaluated for a statement. Used for
+    slow log reporting.
+
+    An examined row is defined as a row that is read and/or evaluated
+    according to a statement condition, including in
+    create_sort_index(). Rows may be counted more than once, e.g., a
+    statement including ORDER BY could possibly evaluate the row in
+    filesort() before reading it for e.g. update.
   */
   ha_rows    examined_row_count;
 
diff --git a/sql/sql_delete.cc b/sql/sql_delete.cc
index 7e91a37257b..cc29b6f1b6b 100644
--- a/sql/sql_delete.cc
+++ b/sql/sql_delete.cc
@@ -248,6 +248,7 @@ bool mysql_delete(THD *thd, TABLE_LIST *table_list, COND *conds,
         free_underlaid_joins(thd, &thd->lex->select_lex);
         DBUG_RETURN(TRUE);
       }
+      thd->examined_row_count+= examined_rows;
       /*
         Filesort has already found and selected the rows we want to delete,
         so we don't need the where clause
@@ -304,6 +305,7 @@ bool mysql_delete(THD *thd, TABLE_LIST *table_list, COND *conds,
   while (!(error=info.read_record(&info)) && !thd->killed &&
 	 ! thd->is_error())
   {
+    thd->examined_row_count++;
     // thd->is_error() is tested to disallow delete row on error
     if (!(select && select->skip_record())&& ! thd->is_error() )
     {
diff --git a/sql/sql_update.cc b/sql/sql_update.cc
index d8141deba63..69f3a29e923 100644
--- a/sql/sql_update.cc
+++ b/sql/sql_update.cc
@@ -425,6 +425,7 @@ int mysql_update(THD *thd,
       {
 	goto err;
       }
+      thd->examined_row_count+= examined_rows;
       /*
 	Filesort has already found and selected the rows we want to update,
 	so we don't need the where clause
@@ -471,6 +472,7 @@ int mysql_update(THD *thd,
 
       while (!(error=info.read_record(&info)) && !thd->killed)
       {
+        thd->examined_row_count++;
 	if (!(select && select->skip_record()))
 	{
           if (table->file->was_semi_consistent_read())
@@ -577,6 +579,7 @@ int mysql_update(THD *thd,
 
   while (!(error=info.read_record(&info)) && !thd->killed)
   {
+    thd->examined_row_count++;
     if (!(select && select->skip_record()))
     {
       if (table->file->was_semi_consistent_read())