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Document the new limitation: no LOCK IN SHARE MODE with MySQL 5.0.

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Daniel Nichter
2012-12-11 17:31:22 +00:00
parent b41ae476ae
commit b0ad60cdfa
1 changed files with 23 additions and 0 deletions
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bin/pt-online-schema-change
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@@ -10087,6 +10087,29 @@ names when creating the new table. For example, to drop this contraint:
You must specify C<--alter "DROP FOREIGN KEY _fk_foo">.
=item *
The tool does not use C<LOCK IN SHARE MODE> with MySQL 5.0 because it can
cause a slave error which breaks replication:
Query caused different errors on master and slave. Error on master:
'Deadlock found when trying to get lock; try restarting transaction' (1213),
Error on slave: 'no error' (0). Default database: 'pt_osc'.
Query: 'INSERT INTO pt_osc.t (id, c) VALUES ('730', 'new row')'
The error happens when converting a MyISAM table to InnoDB because MyISAM
is non-transactional but InnoDB is transactional. MySQL 5.1 and newer
handle this case correctly, but testing reproduces the error 5% of the time
with MySQL 5.0.
This is a MySQL bug, similar to L<http://bugs.mysql.com/bug.php?id=45694>,
but there is no fix or workaround in MySQL 5.0. Without C<LOCK IN SHARE MODE>,
tests pass 100% of the time, so the risk of data loss or breaking replication
should be negligible.
B<Be sure to verify the new table if using MySQL 5.0 and converting
from MyISAM to InnoDB!>
=back
=item --alter-foreign-keys-method