It seems these days if anyone knows anything about tuning InnoDB, it’s that you MUST tune your innodb_buffer_pool_size to 80% of your physical memory. This is such prolific tuning advice, it seems engrained in many a DBA’s mind.  The MySQL manual to this day refers to this rule, so who can blame the DBA?  The question is: does it makes sense?

What uses the memory on your server?

Before we question such advice, let’s consider what can take up RAM in a typical MySQL server in their broad categories.  This list isn’t necessarily complete, but I think it outlines the large areas a MySQL server could consume memory.

• OS Usage: Kernel, running processes, filesystem cache, etc.
• MySQL fixed usage: query cache, InnoDB …

I just returned home after attending the International PHP Conference 2004 and MySQL ComCon Europe 2004 conferences.

Monday
After a convenient ride with the ICE-3 high-speed train from Siegburg to Frankfurt am Main / Airport (about 40 minutes) and a short ride with a shuttle bus to the hotel (about 10 minutes) I arrived at the conference venue just in time for the first coffee break of the day.

Following the first "Hello!"s with my fellow PHP developers …