Proposed fix for bug #17764 "Trigger crashes MyISAM table"

A table with an on insert trigger was reported as crashed when the insert
was processed with bulk insert mode on (handler::start_bulk_insert).
The trigger was also selecting from the same table, and that caused
the "crash".
The same problem was present when an insert statement, which was processed
in bulk mode, also used a stored function that was reading the same table.

This fix disables bulk inserts if a statement uses functions or invokes
triggers. Implementing more granular checks will require much more code and
therefore can hardly be done in 5.0


mysql-test/r/trigger.result:
  Added test bug #17764 "Trigger crashes MyISAM table".
mysql-test/t/trigger.test:
  Added test bug #17764 "Trigger crashes MyISAM table".
sql/sql_insert.cc:
  We should not start bulk inserts for INSERT (or similar) statement if it uses
  functions or invokes triggers since they may access to the same table and
  therefore should not see its inconsistent state created by this optimization.
sql/sql_load.cc:
  We should not start bulk inserts for INSERT (or similar) statement if it uses
  functions or invokes triggers since they may access to the same table and
  therefore should not see its inconsistent state created by this optimization.

2 files changed, 19 insertions, 9 deletions

diff --git a/sql/sql_insert.cc b/sql/sql_insert.cc
index eb74144c1ea..6383e87a1c8 100644
--- a/sql/sql_insert.cc
+++ b/sql/sql_insert.cc
@@ -404,11 +404,15 @@ bool mysql_insert(THD *thd,TABLE_LIST *table_list,
     let's *try* to start bulk inserts. It won't necessary
     start them as values_list.elements should be greater than
     some - handler dependent - threshold.
+    We should not start bulk inserts if this statement uses
+    functions or invokes triggers since they may access
+    to the same table and therefore should not see its
+    inconsistent state created by this optimization.
     So we call start_bulk_insert to perform nesessary checks on
     values_list.elements, and - if nothing else - to initialize
     the code to make the call of end_bulk_insert() below safe.
   */
-  if (lock_type != TL_WRITE_DELAYED)
+  if (lock_type != TL_WRITE_DELAYED && !thd->prelocked_mode)
     table->file->start_bulk_insert(values_list.elements);
 
   thd->no_trans_update= 0;
@@ -534,7 +538,7 @@ bool mysql_insert(THD *thd,TABLE_LIST *table_list,
   else
 #endif
   {
-    if (table->file->end_bulk_insert() && !error)
+    if (!thd->prelocked_mode && table->file->end_bulk_insert() && !error)
     {
       table->file->print_error(my_errno,MYF(0));
       error=1;
@@ -2181,7 +2185,7 @@ select_insert::prepare(List<Item> &values, SELECT_LEX_UNIT *u)
     lex->current_select->options|= OPTION_BUFFER_RESULT;
     lex->current_select->join->select_options|= OPTION_BUFFER_RESULT;
   }
-  else
+  else if (!thd->prelocked_mode)
   {
     /*
       We must not yet prepare the result table if it is the same as one of the 
@@ -2189,6 +2193,8 @@ select_insert::prepare(List<Item> &values, SELECT_LEX_UNIT *u)
       indexes on the result table, which may be used during the select, if it
       is the same table (Bug #6034). Do the preparation after the select phase
       in select_insert::prepare2().
+      We won't start bulk inserts at all if this statement uses functions or
+      should invoke triggers since they may access to the same table too.
     */
     table->file->start_bulk_insert((ha_rows) 0);
   }
@@ -2229,7 +2235,8 @@ select_insert::prepare(List<Item> &values, SELECT_LEX_UNIT *u)
 int select_insert::prepare2(void)
 {
   DBUG_ENTER("select_insert::prepare2");
-  if (thd->lex->current_select->options & OPTION_BUFFER_RESULT)
+  if (thd->lex->current_select->options & OPTION_BUFFER_RESULT &&
+      !thd->prelocked_mode)
     table->file->start_bulk_insert((ha_rows) 0);
   DBUG_RETURN(0);
 }
@@ -2332,7 +2339,8 @@ void select_insert::send_error(uint errcode,const char *err)
     */
     DBUG_VOID_RETURN;
   }
-  table->file->end_bulk_insert();
+  if (!thd->prelocked_mode)
+    table->file->end_bulk_insert();
   /*
     If at least one row has been inserted/modified and will stay in the table
     (the table doesn't have transactions) (example: we got a duplicate key
@@ -2367,7 +2375,7 @@ bool select_insert::send_eof()
   int error,error2;
   DBUG_ENTER("select_insert::send_eof");
 
-  error=table->file->end_bulk_insert();
+  error= (!thd->prelocked_mode) ? table->file->end_bulk_insert():0;
   table->file->extra(HA_EXTRA_NO_IGNORE_DUP_KEY);
 
   /*
@@ -2450,7 +2458,8 @@ select_create::prepare(List<Item> &values, SELECT_LEX_UNIT *u)
   thd->cuted_fields=0;
   if (info.ignore || info.handle_duplicates != DUP_ERROR)
     table->file->extra(HA_EXTRA_IGNORE_DUP_KEY);
-  table->file->start_bulk_insert((ha_rows) 0);
+  if (!thd->prelocked_mode)
+    table->file->start_bulk_insert((ha_rows) 0);
   thd->no_trans_update= 0;
   thd->abort_on_warning= (!info.ignore &&
                           (thd->variables.sql_mode &
diff --git a/sql/sql_load.cc b/sql/sql_load.cc
index cc724c102a4..0a667c887ef 100644
--- a/sql/sql_load.cc
+++ b/sql/sql_load.cc
@@ -356,7 +356,8 @@ bool mysql_load(THD *thd,sql_exchange *ex,TABLE_LIST *table_list,
     if (ignore ||
 	handle_duplicates == DUP_REPLACE)
       table->file->extra(HA_EXTRA_IGNORE_DUP_KEY);
-    table->file->start_bulk_insert((ha_rows) 0);
+    if (!thd->prelocked_mode)
+      table->file->start_bulk_insert((ha_rows) 0);
     table->copy_blobs=1;
 
     thd->no_trans_update= 0;
@@ -373,7 +374,7 @@ bool mysql_load(THD *thd,sql_exchange *ex,TABLE_LIST *table_list,
       error= read_sep_field(thd, info, table_list, fields_vars,
                             set_fields, set_values, read_info,
 			    *enclosed, skip_lines, ignore);
-    if (table->file->end_bulk_insert() && !error)
+    if (!thd->prelocked_mode && table->file->end_bulk_insert() && !error)
     {
       table->file->print_error(my_errno, MYF(0));
       error= 1;