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MySQL: Five Dials to Set

Jun 12, 2009, 16:29 (0 Talkback[s])
(Other stories by Sean Hull)

"1. Connections

"Connections are typically coming from a web server, as many MySQL databases back internet websites. Here are some of the parameters related to connections, and how to set them. max_connections

"This should be at minimum the sum of the maximum number of apache connections allowed from all your web servers. Keep in mind that each connection uses session memory (see below). max_packet_allowed

"The maximum packet size is typically the size of your largest dataset you'll need to return in one chunk. If you're using mysqldump remote, it may need to be larger. aborted_connects

"Check this system status counter, and be sure it is not increasing. If it is, your clients are getting errors connecting. thread_cache_size

"Incoming connections create a new thread in mysql each time they are opened. Since opening and closing connections in mysql is very cheap (resource-wise) and fast, persistent connections aren't as typical as they are with other databases such as Oracle. However, having threads pre-created does save some time, and that's what the mysql thread cache is for.

"Keep an eye on threads_created and if it is increasing, make your thread cache bigger. It doesn't cost much in terms of memory to have 25, 50 or 100 thread_cache_size."

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