From ee4452dba4bb9dac188390b39314e0416f53e3c9 Mon Sep 17 00:00:00 2001
From: unknown <holyfoot/hf@mysql.com/hfmain.(none)>
Date: Wed, 31 Oct 2007 16:01:29 +0400
Subject: [PATCH] Bug #31893 Partitions: crash if subpartitions and engine
 change.

The new default database engine for altered table was reassigned to
the old one. That's wrong thing by itself, and (as the engine
for a subpartition gets that new value) leads to DBUG_ASSERTION
in mysql_unpack_partition()


mysql-test/r/partition.result:
  Bug #31893 Partitions: crash if subpartitions and engine change.

  test result
mysql-test/t/partition.test:
  Bug #31893 Partitions: crash if subpartitions and engine change.

  test case
sql/sql_partition.cc:
  Bug #31893 Partitions: crash if subpartitions and engine change.

  Don't change part_info->default_engine_type if it's already set
---
 mysql-test/r/partition.result | 14 ++++++++++++++
 mysql-test/t/partition.test   | 11 +++++++++++
 sql/sql_partition.cc          |  5 ++++-
 3 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/mysql-test/r/partition.result b/mysql-test/r/partition.result
index 4e4bd0bbc0a..e39e84fdd69 100644
--- a/mysql-test/r/partition.result
+++ b/mysql-test/r/partition.result
@@ -1291,4 +1291,18 @@ t1	CREATE TABLE `t1` (
   `b` int(11) DEFAULT NULL
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1 /*!50100 PARTITION BY RANGE (b) (PARTITION p1 VALUES LESS THAN (10) ENGINE = MyISAM, PARTITION p2 VALUES LESS THAN (20) ENGINE = MyISAM) */
 drop table t1, t2;
+create table t1 (int_column int, char_column char(5))
+PARTITION BY RANGE (int_column) subpartition by key (char_column)
+(PARTITION p1 VALUES LESS THAN (5) ENGINE = InnoDB);
+Warnings:
+Warning	1286	Unknown table engine 'InnoDB'
+alter table t1 PARTITION BY RANGE (int_column) subpartition by key (char_column)
+(PARTITION p1 VALUES LESS THAN (5) ENGINE = myisam);
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `int_column` int(11) DEFAULT NULL,
+  `char_column` char(5) DEFAULT NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1 /*!50100 PARTITION BY RANGE (int_column) SUBPARTITION BY KEY (char_column) (PARTITION p1 VALUES LESS THAN (5) ENGINE = MyISAM) */
+drop table t1;
 End of 5.1 tests
diff --git a/mysql-test/t/partition.test b/mysql-test/t/partition.test
index 2906b4640cd..82a8759e910 100644
--- a/mysql-test/t/partition.test
+++ b/mysql-test/t/partition.test
@@ -1528,4 +1528,15 @@ PARTITION BY RANGE (b) (
 show create table t1;
 drop table t1, t2;
 
+#
+# Bug #31893 Partitions: crash if subpartitions and engine change
+#
+create table t1 (int_column int, char_column char(5))
+  PARTITION BY RANGE (int_column) subpartition by key (char_column)
+  (PARTITION p1 VALUES LESS THAN (5) ENGINE = InnoDB);
+alter table t1 PARTITION BY RANGE (int_column) subpartition by key (char_column)
+  (PARTITION p1 VALUES LESS THAN (5) ENGINE = myisam);
+show create table t1;
+drop table t1;
+
 --echo End of 5.1 tests
diff --git a/sql/sql_partition.cc b/sql/sql_partition.cc
index 0cc2cac2a1a..e5466599429 100644
--- a/sql/sql_partition.cc
+++ b/sql/sql_partition.cc
@@ -5031,7 +5031,10 @@ the generated partition syntax in a correct manner.
         *partition_changed= TRUE;
       }
       if (create_info->db_type == partition_hton)
-        part_info->default_engine_type= table->part_info->default_engine_type;
+      {
+        if (!part_info->default_engine_type)
+          part_info->default_engine_type= table->part_info->default_engine_type;
+      }
       else
         part_info->default_engine_type= create_info->db_type;
       if (check_native_partitioned(create_info, &is_native_partitioned,