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Re: logical OR on two fields in a table in a database
Posted by: Erin ONeill
Date: June 30, 2005 01:08PM

Wow good stuff! my poor brain with a cold will have to spend some time with this.

So far the table caching is how I expected it to behave so I'm gonna have to dig deeper and really understand this and the impact on the OS. My table_cache has been set to 640 though it started at 380. My open table status stuff looks like this:
Open tables 640
Open files 1130
Open streams 0
Opened tables 18379

When I set the table_cache closer to the formula of max_connections * tables in joins the Opened tables seemed to increase at a very slow rate. When the number was dropped down to 380 it began to increase at a pretty dramatic rate. The number above is from a server running 1 day, 11 hours, 8 min and 14 sec. which is approx. 538 tables an hour. The table_cache setting was at 380 for the first 8 or 9 hours and then increased to 680. While the setting was at 2400 (on another day)this increase seemed much slower (but I don't have enough stats or clean enough stats to give an accurate number). AND the database was quite zippy. then it crashed!

I'm gonna have to read up on why it crashed the server.

The query cache is another kettle of fish! :) love love this setting! It was set on but then the size was set to 0. It was finally set to 32, then 64 and now at 96. Changing this and thread_caching made a dramatic change in the speed of the server. Now I just have to get more memory so I can up the query cache and key buffer! :)

On to read mysql code!

Thanks jay for such thought provoking answers. The books are vague about many of the server parameters. They do go into depth about some just not ALL! :)

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