[#MDEV-8364] wsrep_dirty_reads not possible with wsrep_sync

1. Three node galera cluster, with wsrep_sync_wait=1 in /etc/my.cnf
2. Kill two of three nodes
3. Connect to last node, try to enable dirty reads and select data from it. You get a lock wait timeout exception (1205). SET wsrep_sync_wait=0 gets you halfway but you still cannot access table data.

Server version: 10.0.17-MariaDB-wsrep-log

Copyright (c) 2000, 2015, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

MariaDB [(none)]> select 1;

ERROR 1047 (08S01): WSREP has not yet prepared node for application use

MariaDB [(none)]> set wsrep_dirty_reads=1;

Query OK, 0 rows affected (0.00 sec)

MariaDB [(none)]> select 1;

ERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction

MariaDB [(none)]> set wsrep_sync_wait=0;

Query OK, 0 rows affected (0.00 sec)

MariaDB [(none)]> select 1;

+---+

| 1 |

+---+

| 1 |

+---+

1 row in set (0.00 sec)

MariaDB [(none)]> use mysql;

ERROR 1047 (08S01): WSREP has not yet prepared node for application use

MariaDB [(none)]> select @@global.wsrep_sync_wait;

+--------------------------+

| @@global.wsrep_sync_wait |

+--------------------------+

|                        1 |

+--------------------------+

1 row in set (0.00 sec)

MariaDB [(none)]> set @@global.wsrep_sync_wait=0;

Query OK, 0 rows affected (0.00 sec)

MariaDB [(none)]> use mysql;

ERROR 1047 (08S01): WSREP has not yet prepared node for application use

[MDEV-8364] wsrep_dirty_reads not possible with wsrep_sync_wait (deadlock) Created: 2015-06-23 Updated: 2015-10-14 Resolved: 2015-10-14
Status:	Closed
Project:	MariaDB Server
Component/s:	Galera
Affects Version/s:	10.0.17-galera
Fix Version/s:	N/A

[MDEV-8364] wsrep_dirty_reads not possible with wsrep_sync_wait (deadlock) Created: 2015-06-23 Updated: 2015-10-14 Resolved: 2015-10-14