From 77ab3b28a7ab7f0c7b65ae877f4697d0efe7e00f Mon Sep 17 00:00:00 2001
From: "svoj@may.pils.ru" <>
Date: Thu, 1 Jun 2006 18:08:57 +0500
Subject: [PATCH] BUG#19192 - CHECK TABLE EXTENDED / REPAIR TABLE show no
 errors.             ALTER TABLE crashes Executing fast alter table (one that
 doesn't need to copy data) on tables created by mysql versions prior to
 4.0.25 could result in posterior server crash when accessing these tables.

There was a bug prior to mysql-4.0.25. Number of null fields was
calculated incorrectly. As a result frm and data files gets out of
sync after fast alter table. There is no way to determine by which
mysql version (in 4.0 and 4.1 branches) table was created, thus we
disable fast alter table for all tables created by mysql versions
prior to 5.0 branch.
See BUG#6236.
---
 sql/sql_table.cc | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/sql/sql_table.cc b/sql/sql_table.cc
index 9ec8e8db1fb..275cfbaa088 100644
--- a/sql/sql_table.cc
+++ b/sql/sql_table.cc
@@ -3614,12 +3614,21 @@ bool mysql_alter_table(THD *thd,char *new_db, char *new_name,
     their layout. See Field_string::type() for details.
     Thus, if the table is too old we may have to rebuild the data to
     update the layout.
+
+    There was a bug prior to mysql-4.0.25. Number of null fields was
+    calculated incorrectly. As a result frm and data files gets out of
+    sync after fast alter table. There is no way to determine by which
+    mysql version (in 4.0 and 4.1 branches) table was created, thus we
+    disable fast alter table for all tables created by mysql versions
+    prior to 5.0 branch.
+    See BUG#6236.
   */
   need_copy_table= (alter_info->flags &
                     ~(ALTER_CHANGE_COLUMN_DEFAULT|ALTER_OPTIONS) ||
                     (create_info->used_fields &
                      ~(HA_CREATE_USED_COMMENT|HA_CREATE_USED_PASSWORD)) ||
                     table->s->tmp_table ||
+                    !table->s->mysql_version ||
                     (table->s->frm_version < FRM_VER_TRUE_VARCHAR && varchar));
   create_info->frm_only= !need_copy_table;