Hey thanks for the example, I think your phrasing was a little unclear but clearly you know what you're talking about, so I reversed my downvote into an upvote.

Hey thanks for the example, I think your phrasing was a little unclear but clearly you know what you're talking about, so I reversed my downvote into an upvote. [edit: crap now I can't do that the buttons gone] I also tried to look into the behavior and it turns out what we're running into here is a 'gap lock' necessary to support ranges in statement based replication (the default). You can change the behavior if you're using row based replication its just not the default. For instance if the second transaction in your example was "BETWEEN 7 and 10" then both transactions would run concurrently no problem, its acting like row+1 level locking. Here's a much more detailed explanation: http://www.mysqlperformanceblog.com/2012/03/27/innodbs-gap-locks/ http://www.mysqlperformanceblog.com/2012/03/27/innodbs-gap-l...