bk commit into 5.0 tree (kroki:1.2235) BUG#21013

[kroki]

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ChangeSet@stripped, 2006-07-14 22:45:48+04:00, kroki@stripped +1 -0
  Bug#21013: Performance Degrades when importing data that uses Trigger
             and Stored Procedure
  
  The essence of the bug was that for every re-execution of stored
  routine or prepared statement new items for character set conversions
  were created, thus increasing the number of items and the time of their
  processing, and creating memory leak.
  
  No test case is provided since current test suite can't cover such type
  of bugs.

  sql/item.cc@stripped, 2006-07-14 22:42:40+04:00, kroki@stripped +3 -2
    Switch arena only when in statement prepare mode.  Subsequent executions
    will use cached item tree.

# This is a BitKeeper patch.  What follows are the unified diffs for the
# set of deltas contained in the patch.  The rest of the patch, the part
# that BitKeeper cares about, is below these diffs.
# User:	kroki
# Host:	moonlight.intranet
# Root:	/home/tomash/src/mysql_ab/mysql-5.0-bug21013

--- 1.227/sql/item.cc	2006-07-14 22:45:57 +04:00
+++ 1.228/sql/item.cc	2006-07-14 22:45:57 +04:00
@@ -1418,7 +1418,8 @@
     In case we're in statement prepare, create conversion item
     in its memory: it will be reused on each execute.
   */
-  arena= thd->activate_stmt_arena_if_needed(&backup);
+  arena= thd->is_stmt_prepare() ? thd->activate_stmt_arena_if_needed(&backup)
+                                : NULL;
 
   for (i= 0, arg= args; i < nargs; i++, arg+= item_sep)
   {
@@ -1453,7 +1454,7 @@
       been created in prepare. In this case register the change for
       rollback.
     */
-    if (arena && arena->is_conventional())
+    if (arena)
       *arg= conv;
     else
       thd->change_item_tree(arg, conv);