MySQL Performance Blog

I finally got my visa so I’m going to MySQL Developers meeting in Heidelberg, Germany next week.
Hopefully it will be great source of “technical insight” information, either from organized sessions or from developers themselves.

Plus I’m looking forward meeting a lot of friends our where both MySQL Developers and active community members.

If you like to compile MySQL from sources by yourself, for different needs, like debugging, testing etc, you probably can face this issue.

What I usually do to fast compile and test is

1. ./configure --prefix=/dir/to/mysql
2. make
3. make install

and then, for example, load the dump of InnoDB from previous version:

mysql testdatabase < dump.sql

I bet you will not notice all your tables now is MyISAM. Why?

Monty Taylor posted interesting investigation of the fact read_buffer_size variable affects connection speed.

This is not something you would expect right ? me too. Not only global user data is expected to be cached on startup but even if it is not why would you do full table scan to fetch single user information ? Something is fishy here and perhaps bug needs to be filed either resulting in fixes or docummentation updates.

Returning to my post about memory consumption with Stored Function at this moment I want to annul that post. Trying to repeat described behavoir I cannot repeat that again and probably there was something wrong with the whole box, not MySQL. I apologize if it was confusing. Although I am almost sure this topic will popup somewhen.

HighLoad.RU is the conference focused on Building High Performance Systems and has speakers from most of top Russian Internet companies.

It is taking place in Moscow, Russia 24-25 of September and you should know a bit of Russian to attend

During last one and a half year we had pretty good track record with MySQL Performance Blog - there were times when site was slow (especially when backup was running) but I do not remember significant downtime, until today we went down for few hours.

Vadim asked me yesterday to update Microslow patch for 5.1.21, because the previous one I wrote for 5.1.20 failed to apply correctly on the new MySQL release. Imagine the expression on my face after I unpacked the sources and found out that MySQL incorporated the patch to their release. So it’s a built-in feature now in the 5.1 line. So far I noticed one addition to my code which is logging the microtime statistics into TABLE type log storage.

Maciek

I believe we wrote about this before, but this topic popups again and again.
Today I've read opinion that if we have clause WHERE has_something=1 we should have index on column `has_something` (the column has two values 0 and 1).

In reality the right answer is not so simple.

Let's look next table

Not so long time ago I had task to update string column in table with 10mil+ rows, and, as the manipulation was non-trivial, I decided this task is good to try Stored Function. Function written - go ahead. Since 5 min I got totally frozen box with no free memory and giant swap.

The case was worth to look deeply - let's try simple table

Jan has a good article about finding the row matching some value in the group:

I noticed today if you go to Yahoo.com and type MySQL to Search field it gives you suggestions for MySQL, which are:

* loading javascript arrays with mysql data
* mysql performance blog
* mysql download
* mysql administrator download
* mysql front download

It may not be best search suggestions but it is cool to see our blog name to make it in the top of the list.
Too bad few Geeks use Yahoo for search so most of our search engine traffic comes from Google.

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 from the table by the key we think this is simple query, while can be real monster instead with complexity hidden away in VIEW definition.