miércoles, 20 de febrero de 2008

Migrating the platform to mysql 5.1

Last week I began the actualization of the server platform (CentOS versión, MySQL version, GFS version) for the dwh I manage.

Everything went quite right except the MySQL upgrade (from 5.0 to 5.1). As you may know MyISAM tables are composed by three files: a frm file that contains information of the table structure, a myd file that contains the data and a myi file that contains the index data. The MyISAM structure didn't change from 5.0 to 5.1 so I just did a copy of the files....but that was not totally true for ARCHIVE engine...

The ARCHIVE engine is a compressed data table which allow less disk usage (you should know disk usage is important for DWH :)) ...the scans are fater because rows are compressed and the server can read more rows from disk (obviously with the penalty of processor time for decompression). I use ARCHIVE for historic and less frequently queried tables...

So what was the problem? MySQL 5.1 crashes on some (not all) ARCHIVE tables....I am working around this problem.....

No hay comentarios: