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Bug #29154: LOCK TABLES is not atomic when >1 InnoDB tables are locked

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LOCK TABLES takes a list of tables to lock. It may lock several 
  tables successfully and then encounter a tables that it can't lock, 
  e.g. because it's locked. In such case it needs to undo the locks on
  the already locked tables. And it does that. But it has also notified
  the relevant table storage engine handlers that they should lock.
  The only reliable way to ensure that the table handlers will give up
  their locks is to end the transaction. This is what UNLOCK TABLE 
  does : it ends the transaction if there were locked tables by LOCK 
  tables.
  It is possible to end the transaction when the lock fails in 
  LOCK TABLES because LOCK TABLES ends the transaction at its start 
  already. 
  Fixed by ending (again) the transaction when LOCK TABLES fails to
  lock a table.
This commit is contained in:
gkodinov/kgeorge@magare.gmz
2007-06-25 10:44:52 +03:00
parent 8a6b7f7cca
commit f93607d2ea
3 changed files with 62 additions and 1 deletions
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15
mysql-test/r/innodb_mysql.result
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@ -661,4 +661,19 @@ UPDATE t3 SET a = 'us' WHERE a = 'uk';
SELECT * FROM t3 WHERE a = 'uk';
a
DROP TABLE t1,t2,t3;
CREATE TABLE t1 (a INT) ENGINE=InnoDB;
CREATE TABLE t2 (a INT) ENGINE=InnoDB;
switch to connection c1
SET AUTOCOMMIT=0;
INSERT INTO t2 VALUES (1);
switch to connection c2
SET AUTOCOMMIT=0;
LOCK TABLES t1 READ, t2 READ;
ERROR HY000: Lock wait timeout exceeded; try restarting transaction
switch to connection c1
COMMIT;
INSERT INTO t1 VALUES (1);
switch to connection default
SET AUTOCOMMIT=default;
DROP TABLE t1,t2;
End of 5.0 tests