From ca00a985a1e3df3e2fe71e0eec125fdcfa09f1a9 Mon Sep 17 00:00:00 2001
From: unknown <kroki/tomash@moonlight.intranet>
Date: Mon, 17 Jul 2006 14:48:40 +0400
Subject: [PATCH] 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.


mysql-test/r/sp.result:
  Add result for bug#21013: Performance Degrades when importing data
  that uses Trigger and Stored Procedure.
mysql-test/t/sp.test:
  Add test case for bug#21013: Performance Degrades when importing data
  that uses Trigger and Stored Procedure.
sql/item.cc:
  Switch arena only when in statement prepare mode.  Subsequent executions
  will use cached item tree.
---
 mysql-test/r/sp.result | 12 ++++++++++++
 mysql-test/t/sp.test   | 27 +++++++++++++++++++++++++++
 sql/item.cc            |  5 +++--
 3 files changed, 42 insertions(+), 2 deletions(-)

diff --git a/mysql-test/r/sp.result b/mysql-test/r/sp.result
index 96bf2f01f86..10556bf31a2 100644
--- a/mysql-test/r/sp.result
+++ b/mysql-test/r/sp.result
@@ -5057,4 +5057,16 @@ concat('data was: /', var1, '/')
 data was: /1/
 drop table t3|
 drop procedure bug15217|
+DROP PROCEDURE IF EXISTS bug21013 |
+CREATE PROCEDURE bug21013(IN lim INT)
+BEGIN
+DECLARE i INT DEFAULT 0;
+WHILE (i < lim) DO
+SET @b = LOCATE(_latin1'b', @a, 1);
+SET i = i + 1;
+END WHILE;
+END |
+SET @a = _latin2"aaaaaaaaaa" |
+CALL bug21013(10) |
+DROP PROCEDURE bug21013 |
 drop table t1,t2;
diff --git a/mysql-test/t/sp.test b/mysql-test/t/sp.test
index 25c96042e6f..41da4eb9222 100644
--- a/mysql-test/t/sp.test
+++ b/mysql-test/t/sp.test
@@ -5962,6 +5962,33 @@ call bug15217()|
 drop table t3|
 drop procedure bug15217|
 
+
+#
+# BUG#21013: Performance Degrades when importing data that uses
+# Trigger and Stored Procedure
+#
+# This is a performance and memory leak test.  Run with large number
+# passed to bug21013() procedure.
+#
+--disable_warnings
+DROP PROCEDURE IF EXISTS bug21013 |
+--enable_warnings
+
+CREATE PROCEDURE bug21013(IN lim INT)
+BEGIN
+  DECLARE i INT DEFAULT 0;
+  WHILE (i < lim) DO
+    SET @b = LOCATE(_latin1'b', @a, 1);
+    SET i = i + 1;
+  END WHILE;
+END |
+
+SET @a = _latin2"aaaaaaaaaa" |
+CALL bug21013(10) |
+
+DROP PROCEDURE bug21013 |
+
+
 #
 # BUG#NNNN: New bug synopsis
 #
diff --git a/sql/item.cc b/sql/item.cc
index 511ea1ffb44..db8a2985cca 100644
--- a/sql/item.cc
+++ b/sql/item.cc
@@ -1418,7 +1418,8 @@ bool agg_item_charsets(DTCollation &coll, const char *fname,
     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 @@ bool agg_item_charsets(DTCollation &coll, const char *fname,
       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);