I’ve been seeing a lot of interest in pt-online-schema-change (nonblocking MySQL schema changes), with a lively discussion on the mailing list (which I think I’m not keeping up with…) and a couple of bug reports filed. I’m really interested whether people have tested it rigorously to ensure that it maintains your data integrity. I have done so, and there is a set of tests for it in the codebase, but nothing replaces real-world testing. If you find any problems or have questions, please address them to the percona-discussion Google Group.