Reason 147 why MySQL is not my favourite RDBMS

There are three components to my waypoint generator

  • A set of scripts to load or reload some of the data when an update comes in.
  • A set of scripts that actually generates the databases.
  • A web interface.

All three components are written in Perl, and all access the same database. As mentioned previously, I’m using MySQL because PostgreSQL was too slow on the limited resources I have on my Linode.

Last night, I ran one of the load scripts, and while it was running I tried to access the web interface. The web interface start up accesses and updates a couple of “session information” tables, which the load scripts have no reason to access. So somebody tell me why the web interface startup timed out with the error:

[Wed Jun 08 22:08:37 2005] [error] [client] FastCGI: server "/config_backup/" stderr: DBD::mysql::st execute failed: Lock wait timeout exceeded; try restarting transaction at /config_backup/ line 312.

Line 312 in is a line that deletes from the table sess_main. And like I said, nobody else should be updating it. So why the hell should the fact that a load script is running cause a lock wait timeout on that table?