July 24, 2014

Interesting MySQL and PostgreSQL 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 […]

BoardReader – Forum Search Engine

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 […]

Trailing spaces in MySQL

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. […]

Covering index and prefix indexes

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. […]

Opening Tables scalability

I was restarting MySQL on box with 50.000 of Innodb tables and again it took couple of hours to reach decent performance because of “Opening Tables” stage was taking long. Part of the problem is Innodb is updating stats on each table open which is possibly expensive operation, but really it is only great test […]

Feature Idea: Finding columns which query needs to access

In query examinations it is often interesting which columns query needs to access to provide result set as it gives you ideas if you can use covering indexes to speed things up or even cache some data by denormalizing tables. So far it has to be done manually – look at SELECT clause, WHERE clause, […]

Rebuilding MySQL Binary

Running RPM based or other packaged MySQL Binary you may have a problem if you would like to rebuild binary for some reason – change some build settings, apply some third party patches or simply try latest snapshot (This time I was both applying patches for Innodb scalability and Vadim’s patches to get proper slow […]

Bug fix of InnoDB scalability problem

I was pretty busy last month with project which will be annonced very soon (I hope), but I can’t miss bug fix of my favorite bug 15815. I wrote about this problem before and also investigated in my presentation. Finally bug fix was pushed into 5.0-bk tree and now I have it in my hands. […]

Trying Archive Storage Engine

Today I noticed one of server used for web request profiling stats logging is taking about 2GB per day for logs, which are written in MyISAM table without indexes. So I thought it is great to try how much archive storage engine could help me in this case.

Are PHP persistent connections evil ?

As you probably know PHP “mysql” extension supported persistent connections but they were disabled in new “mysqli” extension, which is probably one of the reasons some people delay migration to this extension. The reason behind using persistent connections is of course reducing number of connects which are rather expensive, even though they are much faster […]