Memcached + MySQL
brian at tangent.org
Wed Oct 31 22:29:13 UTC 2007
On Oct 31, 2007, at 3:57 AM, Alexander Zaitsev wrote:
> MySQL itself has a bunch of optimization options that effectively
> turn disk reads into memory reads . In your case I would guess that
> following tuning would help:
> 1. Increase MySQL query cache size
> 2. increase key_buffer_size (normal value is 512K).
This really isn't the right mailing list for this, but the above is
not quite right. The query cache is purged pretty constantly with
Innodb (and its very accurate except in the most recent versions).
For MyISAM it is better but I've rarely seen the query cache make any
difference outside of benchmarks.
MyISAM relies on the OS'es ability to cache files. With Innodb it is
a bit better, but on current versions of MySQL the buffer pool, which
you need to really scale, is not really well threaded. This has been
fixed and there are additional fixes in the 5.1 tree around the
autoincrement issues that come up with multi-concurrency.
> MyISAM is also faster than InnoDB, if your application logic
> permits non-transactional DB. MEMORY engine is probably not a good
> idea since you can loose all your data.
Not really. MyISAM is at the mercy of the file system cache. It can
sometimes be faster, but a well tuned Innodb is normally faster for
reads (though not writes...). Write concurrency performance is very
dependent on tuning and the application design. If all you need is a
fast writer use Archive :)
If the user has no need for durability, then memory for many
operations is quite fast. You can do backstore with triggers to
persistent engines if you need it.
Brian "Krow" Aker, brian at tangent.org
http://krow.net/ <-- Me
http://tangent.org/ <-- Software
http://exploitseattle.com/ <-- Fun
You can't grep a dead tree.
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