I forwarded on a list of questions about PBXT to Paul McCullagh today.Â While Paul’s busy answering them, I’d like to announce that Robert Dempsey (InfiniDB storage engine) and Bradley C. Kuszmaul (TokuDB storage engine) have also accepted an interview. If you have any questions about either storage engine, please post them here by Friday […]
If you were interviewing to work at Percona, and I asked you “what does Using filesort mean in EXPLAIN,” what would you say? I have asked this question in a bunch of interviews so far, with smart people, and not one person has gotten it right. So I consider it to be a bad interview […]
I vaguely recall a couple of blog posts recently asking something like “what’s the formula to compute mysqld’s worst-case maximum memory usage?” Various formulas are in wide use, but none of them is fully correct. Here’s why: you can’t write an equation for it.
When doing performance analyzes you often would want to see 95 percentile, 99 percentile and similar values. The “average” is the evil of performance optimization and often as helpful as “average patient temperature in the hospital”. Lets set you have 10000 page views or queries and have average response time of 1 second. What does […]
I read very nice post by Matt today and it has many good insights though I can’t say I agree on all points. First there is a lot of people out where which put it as disk is everything. Remember Paul Tuckfield saying “You should ask how many disks they have instead of how many […]
I start to see applications being built utilizing VIEWs functionality which appeared in MySQL 5.0 and quite frequently VIEWs are used to help in writing the queries – to keep queries simple without really thinking how it affects server performance. Even worse than that – looking at the short table which just gets single row […]
On many web sites you would see a counter how many time given object – blog post, forum thread, image, movie etc was viewed. This is sometimes handy feature but it can be rather expensive from performance point of view. The nasty thing with counters as they are implemented the most trivial way – they […]
This is not freshest news ever but I simply have not yet had a time to comment on it. I already wrote about interesting benchmarks Tweakers.net have done for MySQL and PostgreSQL with different CPUs. I was in contact with Tweakers.net team to see if they miss something obvious in MySQL settings as well as […]
I had found pile of MySQL and PostgreSQL benchmarks on various platforms which I have not seen before. Very interesting reading. It does not share too much information about how MySQL or PostgreSQL was configured or about queries. Furthermore MySQL and PostgreSQL has a bit different implementations (ie SubQueries avoided for MySQL) so do not […]
Starting MySQL 4.1, MySQL had support for what is called derived tables, inline views or basically subselects in the from clause. In MySQL 5.0 support for views was added. These features are quite related to each other but how do they compare in terms of performance ?