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A 5.5 version of the fix for Bug #54360 "Deadlock DROP/ALTER/CREATE

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DATABASE with open HANDLER"

Remove LOCK_create_db, database name locks, and use metadata locks instead.
This exposes CREATE/DROP/ALTER DATABASE statements to the graph-based
deadlock detector in MDL, and paves the way for a safe, deadlock-free
implementation of RENAME DATABASE.

Database DDL statements will now take exclusive metadata locks on
the database name, while table/view/routine DDL statements take
intention exclusive locks on the database name. This prevents race
conditions between database DDL and table/view/routine DDL.
(e.g. DROP DATABASE with concurrent CREATE/ALTER/DROP TABLE)

By adding database name locks, this patch implements
WL#4450 "DDL locking: CREATE/DROP DATABASE must use database locks" and
WL#4985 "DDL locking: namespace/hierarchical locks".

The patch also changes code to use init_one_table() where appropriate.
The new lock_table_names() function requires TABLE_LIST::db_length to
be set correctly, and this is taken care of by init_one_table().

This patch also adds a simple template to help work with 
the mysys HASH data structure.

Most of the patch was written by Konstantin Osipov.
This commit is contained in:
Jon Olav Hauglid
2010-07-01 15:53:46 +02:00
parent 34e409fafa
commit 41a3dfe490
28 changed files with 1300 additions and 652 deletions
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50
mysql-test/r/schema.result
View File

@@ -16,19 +16,21 @@ drop schema foo;
# Bug #48940 MDL deadlocks against mysql_rm_db
#
DROP SCHEMA IF EXISTS schema1;
DROP SCHEMA IF EXISTS schema2;
# Connection default
CREATE SCHEMA schema1;
CREATE SCHEMA schema2;
CREATE TABLE schema1.t1 (a INT);
SET autocommit= FALSE;
INSERT INTO schema1.t1 VALUES (1);
# Connection 2
DROP SCHEMA schema1;
# Connection default
ALTER SCHEMA schema1 DEFAULT CHARACTER SET utf8;
Got one of the listed errors
ALTER SCHEMA schema2 DEFAULT CHARACTER SET utf8;
SET autocommit= TRUE;
# Connection 2
# Connection default
DROP SCHEMA schema2;
#
# Bug #49988 MDL deadlocks with mysql_create_db, reload_acl_and_cache
#
@@ -48,3 +50,47 @@ ERROR HY000: Can't execute the given command because you have active locked tabl
UNLOCK TABLES;
# Connection con2
# Connection default
#
# Bug#54360 Deadlock DROP/ALTER/CREATE DATABASE with open HANDLER
#
CREATE DATABASE db1;
CREATE TABLE db1.t1 (a INT);
INSERT INTO db1.t1 VALUES (1), (2);
# Connection con1
HANDLER db1.t1 OPEN;
# Connection default
# Sending:
DROP DATABASE db1;
# Connection con2
# Connection con1
CREATE DATABASE db2;
ALTER DATABASE db2 DEFAULT CHARACTER SET utf8;
DROP DATABASE db2;
# Connection default
# Reaping: DROP DATABASE db1
#
# Tests for increased CREATE/ALTER/DROP DATABASE concurrency with
# database name locks.
#
DROP DATABASE IF EXISTS db1;
DROP DATABASE IF EXISTS db2;
# Connection default
CREATE DATABASE db1;
CREATE TABLE db1.t1 (id INT);
START TRANSACTION;
INSERT INTO db1.t1 VALUES (1);
# Connection 2
# DROP DATABASE should block due to the active transaction
# Sending:
DROP DATABASE db1;
# Connection 3
# But it should still be possible to CREATE/ALTER/DROP other databases.
CREATE DATABASE db2;
ALTER DATABASE db2 DEFAULT CHARACTER SET utf8;
DROP DATABASE db2;
# Connection default
# End the transaction so DROP DATABASE db1 can continue
COMMIT;
# Connection 2
# Reaping: DROP DATABASE db1
# Connection default;