As I already mentioned in Statement-Based Replication Issues, each slave has a single SQL thread, so all its errors can be tested in a single-threaded MySQL client. Even if you run the multithreaded slave preview, you can always ask it to use a single thread when you’re trying to reproduce an error. If reducing activity to one SQL thread fails to make the problem go away, use the following techniques to fix logic errors on the single thread, then switch to multiple threads again.

It’s easy to re-create a query that caused a slave to fail: just run it using the MySQL command-line utility.

When you get an SQL error on the slave, it stops. SHOW SLAVE STATUS shows the SQL thread error that caused the problem: