I have a problem with a replica. We have 2 servers in a master-master circular replication and each of them has some slaves. All these are mysql 5.0 servers. We now decided to upgrade to mysql 5.6 to take advantage of it’s improvements but we run into an issue. We upgraded one of the slaves to 5.6 and we have a problem because the 5.6 slave doesn’t seem to be using the indexes when executing the statements (we are not yet using row based replication). Any idea what could be the problem or how to debug this issue?