It's no secret that MySQL is widely deployed in most leading web sites.  Everyone knows how successful the LAMP stack has become and that companies like Google, Yahoo, Sabre, Evite, Citysearch all use tons of open source software (including MySQL) to scale their operations.  As important as all of these companies are, I'm most proud of the fact that MySQL is used at Wikipedia.  This is one of the top web sites in the world and not only is it built on open source software (Linux, Apache, MySQL, Lucene) and the MediaWiki project. 

Wikipedia is famous not just for being a highly scalable open source project, but more importantly, it is an open and collaborative repository of human knowledge.  There are more than 1 million articles in the english language edition of Wikipedia and there are smaller versions in more than 100 languages.  And all of …

Arjen’s MySQL Community Journal - HyperThreading? Not on a MySQL server…

I blame the Linux Process Scheduler. At least it’s better than the earlier 2.6 days where things would get shunted a lot from one “cpu” to the other “cpu” for no real reason.

Newer kernel verisons are probably better… but don’t even think of HT and pre-2.6 - that would be funny.

Did you know that... using a CPU with HyperThreading turned on actually makes your MySQL database server slower?

Reason... Well, with real multi-core or multi-CPU, MySQL's connection threads get nicely spread. With HT it looks like you have multiple cores, but you don't really. This possibly causes more overhead given MySQL's multi-threaded architecture? Perhaps others have more insightful clarifications. Anyhow, HT makes things slower on a MySQL server system. Just turn it off and you'll see!

Wouldn't it be cool if the open source RDBMS of the world got together to define a common protocol for debugging stored procedures? This opens up the possibility to share GUI tools and more importantly expertise in making it work to begin with.

This idea dawn on me after reading a thread on stored procedure debugging on the pgsql-hackers list. The other day I was talking to Derick and he mentioned that MySQL also have had an interest in his DBGp debugging protocol. Avid readers of my blog know how fond I am of the idea of using common standards in this area.

So maybe we can get a brought alliance of open source RDBMS developers to work on a common standard? I have been hoping for some solid cooperation materializing …

continuing the recent thread about contenttypes in django I thought I would talk about a feature which got added in the magic removal branch, which doesn’t have as much attention as I think it deserves.

signals and the dispatcher.

signals are way of telling the rest of the world that something happened. If you are interested you simply listen for it (connect in django speak).

take for example my tagging application currently in use on zyons. one of it’s features is that it let’s users store their own tags.

One of the performance improvements I added to this was the creation of a ‘summary’ tag which aggregates which the …

Ramblings » Blog Archive » a bug on failure failure

I blogged about MySQL Bug 17928 a little while ago. Well, I’ve submitted a patch that fixes the problem. I wrote rather a rather detailed explanation in the Changeset comments (and I encourage every body who commits code anywhere to do the same). You can see the patch over on the commits list (or here if you don’t want to sift through the archives).

In all theory it shouldn’t be hard to enable multiple simultaneous backups for Cluster. How useful this would be is very debatable. Arguably of little use of all (it’s a REDO log backup). Of course, testing for this (as we test Node Failure) would start to get horrific. Any good arguments one way or the …

MySQL AB, the developer of the world's most popular open source database, is seeing growing momentum in the UK-Ireland telecommunications sector with Tiger Communications, XOU Solutions and Anam Mobile leading a growing number of businesses adopting MySQL database solutions. MySQL's success in the UK-Ireland telecom sector is reflected elsewhere in Europe. Alcatel, Nokia, Ericsson, Telio and Nortel have all selected MySQL products for important applications in the recent past.

Now it is about time that I start actually putting things on this "blog". Today I have spent time working on Bug#20168 and building 5.1 on Solaris with Sun's compiler. Completed the former, hitting small problems on the latter.

Arjen posted a good note about MyISAM concurrent-insert features, though I should mention concurrent-insert can be cause of
scalablity and peformance problems on SMP boxes, especially on queries processing range-queries. The reason of problems is POSIX read-write locks, which are used to protect key_buffer from concurrent changes and called for each processed row. More info you can get from my UC2006 talk, in short on main platforms (Linux, Solaris, Windows) rw-locks have a bad implementation and too many calls cause waste of CPU in user-space (Solaris) or kernel-space (Linux).

Some results for MyISAM table, query SELECT id FROM sbtest WHERE id BETWEEN N AND N+20000, id - primary …

There are a lot of talks around new coming Ubuntu 6.06, so I decided to make quick benchmarks.
I used sysbench 0.4.6 oltp-read-only workload with 1000000 rows against InnoDB and MyISAM tables.
Such workload is CPU-bound and allows to compare CPU / OS if we are using the same version of MySQL.
So I used MySQL 5.0.22 and my box Dual Core Athlon 3800+, 1Gb of RAM.
For comparison I tested the same workload on my primary Suse 10.0.

Here are results (in transactions per sec, more is better):