Fix bug in INSERT DELAYED with prepared statements

The bug was that if you have two TL_WRITE_DELAYED at the same time,
mi_lock_databases() could be done in the wrong order and we could write the wrong header to the MyISAM index file.


sql/mysql_priv.h:
  Fix bug in insert delayed with prepared statements
sql/sql_base.cc:
  Fix bug in insert delayed with prepared statements
sql/sql_prepare.cc:
  Fix bug in insert delayed with prepared statements
  The bug was that if you have two TL_WRITE_DELAYED at the same time,
  mi_lock_databases() could be done in the wrong order and we could write the wrong header to the MyISAM index file.

1 files changed, 5 insertions, 1 deletions

diff --git a/sql/sql_prepare.cc b/sql/sql_prepare.cc
index ecf01824755..1dc46aef4da 100644
--- a/sql/sql_prepare.cc
+++ b/sql/sql_prepare.cc
@@ -897,8 +897,12 @@ static int mysql_test_insert(Prepared_statement *stmt,
   /*
      open temporary memory pool for temporary data allocated by derived
      tables & preparation procedure
+     Note that this is done without locks (should not be needed as we will not
+     access any data here)
+     If we would use locks, then we have to ensure we are not using
+     TL_WRITE_DELAYED as having two such locks can cause table corruption.
   */
-  if (open_and_lock_tables(thd, table_list))
+  if (open_normal_and_derived_tables(thd, table_list))
   {
     DBUG_RETURN(-1);
   }