Any Mysql gurus in the house?

January 24th, 2005

My server is having some Mysql connection issues. I know that the number of queries has increased exponentially and I am also aware that the server is doing a lot more work. However, I am wondering if I can tweak some Mysql parameters to make things work better. Here are some details:

Mysql frequently runs out of connections. I close every connection after I am done with it, and I try to reduce or break up all my slow queries. The server averages about 10 queries a second and the number of threads hover around mid 90s all the time. I have reduced the max_timeout and the connect errors to try and reduce the number of threads but that does not seem to make much of a difference. I have tried to increase the number of max connections and that just seems to grind the server to a halt. I have tweaked the SQL as far as I can and have looked at optimising the use of SQL. Is there something else that I should be looking at? If this continues I might have to rewrite some of the apps that use the mysql database. Also, as an aside, are the max connections per database or per database server?

PS: The load is NOT being generated by WordPress. There is true load on the server from some other applications that I run in the background.




  1. rayg (1 comments.) says:

    check your thread cache setting. see jeremy’s post:

  2. Mark says:

    Turned up the thread cache size. Time will tell. Thanks Ray, I will post an update soon.

  3. Matt (64 comments.) says:

    High Performance MySQL, also by Zawodny, is a fantastic book that helped me with some issues we ran into with scaling Ping-O-Matic.

  4. Mark says:

    The difference with the cache is small. I will have to keep looking. I might just buy the book since I know it will come in handy sometime.

  5. Matt (64 comments.) says:

    You’ll probably get the most benefit from optimizing the indicies and queries, at least that’s what I’ve found. If you can make the row length fixed that helps too.

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