EmergencyEMERGENCY? Get 24/7 Help Now!

Where to get recent MySQL version ?

 | December 29, 2006 |  Posted In: Insight for DBAs

As you might noticed there are no recent MySQL Community versions available for download from MySQL Download Area This applies both to binaries (which is expected with new polices) but also to the source files which were promised to be available. So what is if you would like to use recent MySQL code while staying […]

Read More

MySQL Session variables and Hints

 | December 28, 2006 |  Posted In: Insight for Developers

MySQL has two ways to find tune execution of particular query. First is MySQL Hints, such as SQL_BIG_RESULT, STRAIGHT_JOIN, FORCE INDEX etc. You place these directly into the query to change how query is executed for example SELECT STRAIGHT_JOIN * FROM A FORCE INDEX(A) JOIN B The other part is session variable. If you know […]

Read More

Innodb locking and Foreign Keys

 | December 12, 2006 |  Posted In: Insight for DBAs

Today I was working with application which uses Innodb and foreign keys and got into locking problems possibly due to foreign keys, so I did a little investigation on that matter. Interesting enough it looks like most people do not think about foreign keys overhead in terms of locking. The overhead about checking referenced table […]

Read More

Using LoadAvg for Performance Optimization

 | December 4, 2006 |  Posted In: Insight for DBAs

Linux and Unixes have excellent metric of system load called “loadavg”. In fact load average is is 3 numbers which correspond to “load average” calculated for one five and 15 minutes. It is computed as exponential moving average so most recent load have more weight in the value than old one. What does Load Average […]

Read More

COUNT(*) for Innodb Tables

 | December 1, 2006 |  Posted In: Insight for Developers

I guess note number one about MyISAM to Innodb migration is warning what Innodb is very slow in COUNT(*) queries. The part which I often however see omitted is fact it only applies to COUNT(*) queries without WHERE clause. So if you have query like SELECT COUNT(*) FROM USER It will be much faster for […]

Read More

Interesting MySQL and PostgreSQL Benchmarks

 | November 30, 2006 |  Posted In: Benchmarks

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 […]

Read More

BoardReader – Forum Search Engine

 | November 29, 2006 |  Posted In: Events and Announcements

One may have notice we were not blogging too much recently, this is because we were quite busy, mainly building BoardReader.com – Search Engine which indexes tens of thousands of forums from all over the world. This project was built by us as consulting project so too bad we do not own it completely but […]

Read More

Trailing spaces in MySQL

 | November 27, 2006 |  Posted In: Insight for Developers

In the past life was easy in MySQL. Both CHAR and VARCHAR types meant the same, only being difference in the sense of fixed or dynamic row length used. Trailing spaces were removed in both cases. With MySQL 5.0 however things changed so now VARCHAR keeps trailing spaces while CHAR columns do not any more. […]

Read More

Covering index and prefix indexes

 | November 23, 2006 |  Posted In: Insight for DBAs

I already wrote in the blog as well mentioned in presentation there is often a choice you have to make between having prefix index – which can be significantly smaller in size and having index being covering index, which means query can be executed using only data from the index without reading the row itself. […]

Read More