We are running a Drupal Commerce site with MariaDB 10.0 and master/slave replication. Because of the way our application works, we end up running in to a ton of deadlocks under heavy load. Apparently this is a fairly common problem for large Drupal Commerce sites.
We've successfully tested changing two settings on our test servers (which are standalone; not master/slave) which has eliminated the deadlock problem:
transaction-isolation = READ-COMMITTED
binlog_format = ROW
My questions are:
1) When we put this change on our production master/slave setup, do we need to apply this to both the master and slave, or just the master?
2) Is there any special sequence we need to do things in? or can we just adjust my.cnf and restart mariadb?
3) Do we need to 'stop slave' while applying this change?