One of the MySQL 5.6 features many people are interested in is Global Transactions IDs (GTIDs). This is for a good reason: Reconnecting a slave to a new master has always been a challenge while it is so trivial when GTIDs are enabled. However, using GTIDs is not only about replacing good old binlog file/position with unique identifiers, it is also using a new replication protocol. And if you are not aware of it, it can bite.
Replication protocols: old vs new
The old protocol is pretty straightforward: the slave connects to a given binary log file at a specific offset, and the master sends all the transactions from there.
The new protocol is slightly different: the slave first sends the range of GTIDs it has executed, and then the master sends every missing transaction. It also guarantees that a transaction with a given …[Read more]