I am constantly referring to the amazing MySQL manual, especially the option and variable reference table. But just as frequently, I want to look up blog posts on variables, or look for content in the Percona documentation or forums. So I present to you what is now my newest Firefox toolbar bookmark: an option and [...]
A micro-benchmark of stored routines in MySQL
August 16, 2009 By 7 Comments
Ever wondered how fast stored routines are in MySQL? I just ran a quick micro-benchmark to compare the speed of a stored function against a “roughly equivalent” subquery. The idea — and there may be shortcomings that are poisoning the results here, your comments welcome — is to see how fast the SQL procedure code [...]
Optimizing repeated subexpressions in MySQL
January 23, 2009 By 11 Comments
How smart is the MySQL optimizer? If it sees an expression repeated many times, does it realize they’re all the same and not calculate the result for each of them? I had a specific case where I needed to find out for sure, so I made a little benchmark. The query looks something like this:
High-Performance Click Analysis with MySQL
December 22, 2008 By 13 Comments
We have a lot of customers who do click analysis, site analytics, search engine marketing, online advertising, user behavior analysis, and many similar types of work. The first thing these have in common is that they’re generally some kind of loggable event. The next characteristic of a lot of these systems (real or planned) is [...]
How expensive is a WHERE clause in MySQL?
October 31, 2008 By 16 Comments
This is a fun question I’ve been wanting to test for some time. How much overhead does a trivial WHERE clause add to a MySQL query? To find out, I set my InnoDB buffer pool to 256MB and created a table that’s large enough to test, but small enough to fit wholly in memory:
Using flow control functions for performance monitoring queries
May 24, 2008 By 12 Comments
I’m not big fan on flow control functions like IF or CASE used in MySQL Queries as they are often abused used to create queries which are poorly readable as well as can hardly be optimized well by MySQL Optimizer. One way I find IF statement very useful is computing multiple aggregates over different set [...]
The MySQL optimizer, the OS cache, and sequential versus random I/O
April 28, 2008 By 17 Comments
In my post on estimating query completion time, I wrote about how I measured the performance on a join between a few tables in a typical star schema data warehousing scenario. In short, a query that could take several days to run with one join order takes an hour with another, and the optimizer chose [...]
MySQL 6.0 vs 5.1 in TPC-H queries
March 25, 2008 By 17 Comments
Last week I played with queries from TPC-H benchmarks, particularly comparing MySQL 6.0.4-alpha with 5.1. MySQL 6.0 is interesting here, as there is a lot of new changes in optimizer, which should affect execution plan of TPC-H queries. In reality only two queries (from 22) have significantly better execution time (about them in next posts), [...]
The tool I’ve been waiting for years
March 18, 2008 By 10 Comments
I’ve just been pointed to the nice tool which I was waiting for years to see. It is fincore – little perl script which allows you to see what pages of file are cached in OS memory. This is really cool.
Top 5 Wishes for MySQL
June 29, 2007 By 10 Comments
About a week ago Marten send me email pointing to his article published on Jays Blog (Come on Marten, it is time for you to get your own blog). I should have replied much earlier but only found time to do that now. So here is my list 1. Be Pluggable Unlike many OpenSource projects [...]
