I noticed that in the latest release of Percona XtraDB Cluster (PXC), the behavior of wsrep_RSU_method changed somewhat. Prior to this release, the variable was GLOBAL only, meaning to use it you would:
mysql> set GLOBAL wsrep_RSU_method='RSU'; mysql> ALTER TABLE ... mysql> set GLOBAL wsrep_RSU_method='TOI';
This had the (possibly negative) side-effect that ALL DDL’s issued on this node would be affected by the setting while in RSU mode.
So, in this latest release, this variable was made to also have a SESSION value, while retaining GLOBAL as well. This has a couple of side-effects that are common to MySQL variables that are both GLOBAL and SESSION:
- The SESSION copy is made from whatever the GLOBAL’s value is when a new connection (session) is …