MySQL Query Cache: still waiting for duplicate query checking

Way, way back in 2005 (4 years and counting) I finally reported a bug into the then MySQL 5.0 about an issue I was seeing (often) on high volume sites where a single query, if not in the query cache, but spawned from two (or more) simultaneous threads would both be executed in full; this is instead of one execution, and then the query cache being populated.

Reference: Bug 15044, and WorkLog 1293.

I had been seeing this for… well, years before hand, but considered it to be “just me”. Since I filed that bug, others have come forward and said they have seen the same issue.

Now, with the Oracle/Sun merge, and Sun having shelled out to “purchase” MySQL, we see a miraculous MySQL 5.4 being drafted together. Its good; but it appears to be a simple crowd pleaser that should have happened years ago – integrate in some very popular performance improvements (notably from Google’s code repository). If code is being contributed, and it works, why wasn’t this done earlier? And if not earlier, why now? Smokescreen? Last ditch effort before the project is canned by its new owner? Of course, this has been circulating for a while; I’m not posting this later after that’s been in the news for a few weeks now.

What is interesting is the “Refactoring MySQL” project being discussed. Where does this leave MySQL 6 – a little abandoned from here. And then with MariaDB and Drizzle now forked and picking up attention (external to MySQL/Sun/Oracle), it seems the entire thing is just becoming a mess. Drizzel is supposed to be the performance version – but with the google patches being integrated, perhaps the core MySQL branded project is catching up?

What’s looking clearer is: Postgres. From my perspective, its worse for MySQL in Debian. Lenny (stable now) has MySQL 5.0. The Experimental repo has 5.1 (5.1.34), but this hasn’t even transitioned to Unstable yet!

Here’s what I’d like to see:

  1. Someone picks up Bug 15044/WorkLog 1293.
  2. 5.4 goes STABLE from MySQL/Sun/Oracle real soon now, with or without my pet qcache bug/feature – it’s a big enough win for multi-core systems as it stands
  3. Debian moves MySQl 5.1 from experimental straight to Unstable – can the mysql-server-5.1 package can coexist with mysql-server-5.0?
  4. Debian also adds, along side the MySQl 5.0 and 5.1 servers, the 5.4 into Unstable, and 6.0 into Experimental.

London Marathon 2009

Poster
Poster
Once again the carnival atmosphere returned to The Island (Isle of Dogs) today, as 35,000+ people ran down our street as part of the London Marathon, including our friend Luke, and our gym instructor Marie-Jane. What a lovely day; sun shining brightly, cool gentle breeze, full tourist boats swanning their way past our flat on the Thames.

We had the 25km marker right out the front of our flat today. Two pads crossed the running track, with four cables protruding from each, connecting with what looked like a scart cable to a yellow box; this contraption was recording each runner as they went past, with an annoying high pitched chirp for each.

This data was probably available from several places; I had tried the Adidas web site, which today seemed to stall under the load. I subscribed for text-message updates on our two friends, however text messages seemed to take up to 30 minutes extra to come through. The web site itself from Adidas was all done in flash, and by design it was impossible to bookmark the runners I was following. Should my mouse run over any of the menus, the main page of the flash app completely disappeared – most disorientating. Adidas, thanks for the effort, but lets get some people with some knowledge of web design involved; how about an RSS feed for my runners? How about a bit more “real-time”?

Lying by the pool in Aqaba, Jordan

Ahhhh. I am lying on a sun lounger by the “summer pool” at the Movenpick Hotel in Aqaba, Jordan. It’s 35* C today, but surprisingly that’s not as bad as I thought it would be. Splish splash, trying not to read email, but then again I have wifi on my blackberry and am chilled… Perhaps its time to try todays “cocktail of the day”, the Zombie – which was yesterdays cocktail of the day too… Must be good!