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Backport of revno: 2617.68.37

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Bug #46654 False deadlock on concurrent DML/DDL with partitions, 
           inconsistent behavior

The problem was that if one connection is running a multi-statement 
transaction which involves a single partitioned table, and another 
connection attempts to alter the table, the first connection gets 
ER_LOCK_DEADLOCK and cannot proceed anymore, even when the ALTER TABLE 
statement in another connection has timed out or failed.

The reason for this was that the prepare phase for ALTER TABLE for 
partitioned tables removed all instances of the table from the table 
definition cache before it started waiting on the lock. The transaction 
running in the first connection would notice this and report ER_LOCK_DEADLOCK. 

This patch changes the prep_alter_part_table() ALTER TABLE code so that 
tdc_remove_table() is no longer called. Instead, only the TABLE instance
changed by prep_alter_part_table() is marked as needing reopen.

The patch also removes an unnecessary call to tdc_remove_table() from 
mysql_unpack_partition() as the changed TABLE object is destroyed by the 
caller at a later point.

Test case added in partition_sync.test.
This commit is contained in:
Jon Olav Hauglid
2009-12-10 14:26:00 +01:00
parent 7d71d71535
commit fb6b5ee462
8 changed files with 112 additions and 24 deletions
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51
mysql-test/t/partition_sync.test
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@@ -39,6 +39,57 @@
#DROP TABLE t1;
--echo #
--echo # Bug #46654 False deadlock on concurrent DML/DDL
--echo # with partitions, inconsistent behavior
--echo #
--disable_warnings
DROP TABLE IF EXISTS tbl_with_partitions;
--enable_warnings
CREATE TABLE tbl_with_partitions ( i INT )
PARTITION BY HASH(i);
INSERT INTO tbl_with_partitions VALUES (1);
connect(con2,localhost,root);
connect(con3,localhost,root);
--echo # Connection 3
connection con3;
LOCK TABLE tbl_with_partitions READ;
--echo # Connection 1
--echo # Access table with disabled autocommit
connection default;
SET AUTOCOMMIT = 0;
SELECT * FROM tbl_with_partitions;
--echo # Connection 2
--echo # Alter table, abort after prepare
connection con2;
set session debug="+d,abort_copy_table";
--error ER_LOCK_WAIT_TIMEOUT
ALTER TABLE tbl_with_partitions ADD COLUMN f INT;
--echo # Connection 1
--echo # Try accessing the table after Alter aborted.
--echo # This used to give ER_LOCK_DEADLOCK.
connection default;
SELECT * FROM tbl_with_partitions;
--echo # Connection 3
connection con3;
UNLOCK TABLES;
--echo # Connection 1
--echo # Cleanup
connection default;
disconnect con2;
disconnect con3;
DROP TABLE tbl_with_partitions;
# Check that all connections opened by test cases in this file are really
# gone so execution of other tests won't be affected by their presence.
--source include/wait_until_count_sessions.inc