In case you missed it here, we are very proud to announce that Drizzle’s transaction log is passing all of our tests.  For quite some time, David Shrewsbury, Stewart Smith, and Joe Daly have been putting a lot of love into the log code.  Please don’t be fooled by Dave’s praise of QA now that the storm has passed…you should have heard the names he called me and the things he plotted when we were rooting these bugs out ; )  However, now that there is a permanent record of his words, I’ll be reminding him about this post the next time my testing becomes a pain in his posterior and I feel him giving me the stink-eye in IRC (heheh)

With that said, we really have been putting tons of effort into making the log rock-solid.  This code will serve as the foundation for Drizzle replication and we can now be assured that any replication solutions will have a reliable log that will reflect the state of the server.  We have been beating up the code with the random query generator.  We have concocted several grammars that throw a variety of queries, in transactions and standalone, at the server.  After we have made the master do some work – we use a variety of connections and per-connection query counts, we produce SQL from the log, populate a validation server with the SQL, then compare Drizzledump files to ensure they match.  You should really check out the transaction_reader utility in drizzle/plugin/transaction_log/utilities – it allows a user to view the raw trx log contents, produce SQL from the log contents, and a few other neat tricks.  I’ll be blogging a bit more about how we used this for testing and troubleshooting very soon.

The transaction log worked well in most cases, the majority of our problems were in rooting out strange behavior around deadlocks and rolled back transactions.  I’d like to once again thank Stewart Smith, of the spork most flaming, for his valued assistance in finding these annoying bugs : )  If anyone wants to take a look at the bugs we’ve killed – you can check them out here.

We are far from being done – some of our next tasks include testing RabbitMQ, tweaking randgen tests to make certain we are totally crash-safe, and a few other things.  In the meantime, our randgen trx log tests run against every branch we intend to merge into trunk, so we’re keeping a close eye on making sure it stays solid.  We’ll keep you posted as our replication testing moves along.  Please keep trying Drizzle and helping us to improve it with your bug reports and feedback.