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Online DDL doesn't seems to work at all in a Galera cluster.
CREATE TABLE test(
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id INT(11) NOT NULL PRIMARY KEY,
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description VARCHAR(20) DEFAULT NULL
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) engine = innodb;
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wsrep_osu_method = 'TOI'; a certification error will be triggered if another session (same or different node) tries to insert.
I kinda expected this, as it would be complex to certificate transactions across the cluster when tables are changing at different speeds.
db01_session1> alter table test add c1 varchar(50), algorithm=inplace, lock=none;
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Query OK, 0 rows affected (12.60 sec)
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Records: 0 Duplicates: 0 Warnings: 0
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db01_session2> insert into test (id, description) select max(id) + 1, 'description' from test;
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ERROR 1213 (40001): Deadlock found when trying to get lock; try restarting transaction
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wsrep_osu_method = 'RSU'; other sessions will wait until DDL has finalized.
Now, this was unexpected... I'm altering only the local node, and I can see Online DDL messages in the log. But the locking seems to be exclusive.
db01_session1> set wsrep_osu_method = 'RSU';
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Query OK, 0 rows affected (0.02 sec)
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db01_session1> alter table test add c1 varchar(20), algorithm=inplace, lock=none;
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Query OK, 0 rows affected (1 min 2.29 sec)
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Records: 0 Duplicates: 0 Warnings: 0
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db01_session2> insert into test (id, description) select max(id) + 1, 'description' from test;
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Query OK, 1 row affected (1 min 1.50 sec) <-- THIS INSERT HAS WAITED FOR THE DDL DURATION
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Records: 1 Duplicates: 0 Warnings: 0
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Log shows messages about Online DDL, and yes, it was inplace but locking.
2017-03-27 10:38:34 140376044201728 [Note] WSREP: Member 1.0 (0a2f533fa3fd) desyncs itself from group
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2017-03-27 10:38:34 140376044201728 [Note] WSREP: Shifting SYNCED -> DONOR/DESYNCED (TO: 10001)
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2017-03-27 10:38:34 140376323062528 [Note] WSREP: Provider paused at 82f3a726-12d7-11e7-80a6-8391c64749a3:10001 (17791)
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2017-03-27 10:38:34 140376323062528 [Note] InnoDB: Online DDL : Start
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2017-03-27 10:38:34 140376323062528 [Note] InnoDB: Online DDL : Start reading clustered index of the table and create temporary files
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2017-03-27 10:38:39 140376323062528 [Note] InnoDB: Online DDL : End of reading clustered index of the table and create temporary files
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2017-03-27 10:38:39 140376323062528 [Note] InnoDB: Online DDL : Start merge-sorting index `PRIMARY` (1 / 1), estimated cost : 20.0000
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2017-03-27 10:38:39 140376323062528 [Note] InnoDB: Online DDL : merge-sorting has estimated 304 runs
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2017-03-27 10:39:00 140376323062528 [Note] InnoDB: Online DDL : End of merge-sorting index `PRIMARY` (1 / 1)
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2017-03-27 10:39:00 140376323062528 [Note] InnoDB: Online DDL : Start building index `PRIMARY` (1 / 1), estimated cost : 30.0000
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2017-03-27 10:39:36 140376323062528 [Note] InnoDB: Online DDL : End of building index `PRIMARY` (1 / 1)
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2017-03-27 10:39:36 140376323062528 [Note] InnoDB: Online DDL : Completed
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2017-03-27 10:39:36 140376323062528 [Note] WSREP: resuming provider at 17791
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2017-03-27 10:39:36 140376323062528 [Note] WSREP: Provider resumed.
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2017-03-27 10:39:36 140376044201728 [Note] WSREP: Member 1.0 (0a2f533fa3fd) resyncs itself to group
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2017-03-27 10:39:36 140376044201728 [Note] WSREP: Shifting DONOR/DESYNCED -> JOINED (TO: 10001)
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2017-03-27 10:39:36 140376044201728 [Note] WSREP: Member 1.0 (0a2f533fa3fd) synced with group.
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2017-03-27 10:39:36 140376044201728 [Note] WSREP: Shifting JOINED -> SYNCED (TO: 10001)
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2017-03-27 10:39:36 140376418814720 [Note] WSREP: Synchronized with group, ready for connections
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2017-03-27 10:39:36 140376418814720 [Note] WSREP: wsrep_notify_cmd is not defined, skipping notification.
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