Galera: Server does not honor metadata locking (even inside the same node)

--connection con1

CREATE TABLE t1 (i INT PRIMARY KEY);

BEGIN;

INSERT INTO t1 VALUES (1);

--connection con2

ALTER TABLE t1 ADD COLUMN b CHAR;

--connection con1

COMMIT;

Normally, in the scenario above the 2nd connection would wait for a metadata lock on t1 until con1 finishes the transaction, or lock_wait_timeout occurs, whichever happens first. However, if server is running as a Galera node, ALTER TABLE is executed right away, despite the locks that con1 holds; and the transaction in con1 will be rejected.

Explicit BEGIN/COMMIT here are just to make the test deterministic, in fact it happens just as well on a single-statement transaction with autocommit.

Limitations page (http://www.codership.com/wiki/doku.php?id=limitations) mentions LOCK statements, but does not say that internal locking is also not supported. Besides, this kind of scenario does not involve any other nodes.

bzr version-info

revision-id: seppo.jaakola@codership.com-20120808224721-89h8nxmfk9uvp708

date: 2012-08-09 01:47:21 +0300

build-date: 2012-08-20 20:31:14 +0400

revno: 3343