[mythtv-users] Slow MySQL query after delete
Wade Maxfield
mythtv at hotblack.co.nz
Fri Sep 7 01:36:36 UTC 2007
>On Sep 6, 2007, at 2:36 PM, f-myth-users at media.mit.edu wrote:
>> Oh, whoops. Hadn't considered that. (Does Myth have a "suggested" or
>> (gulp) "supported" set of storage engines, or is it claimed that any
>> storage engine MySQL supports will "work"? I'm assuming 99% of
>> everybody leaves theirs at the default, but of course we don't know.)
>
>I'm actually curious if there are any performance benefits to using
>one over the other. My understanding is InnoDB's main benefit over
>MyISAM is transaction support, which MythTV doesn't use, so I'm
>guessing no. There may be other factors I'm not thinking of, though.
>
One major difference between them is MyISAM uses table level locking
for updates, while InnoDB uses row level locking. For a system that
does multiple concurrent reads and writes, this could impact things.
And just to throw another variable out there (well 2 actually), there
is a mysql-tuning script I came across a long time ago, and 2 of it's
suggestions for ways to tweak performance with table locking issues
are (direct quote from the script, typos included):
"If you have long running SELECT's against MyISAM tables and perform
frequent updates consider setting 'low_priority_updates=1'
If you have a high concurrentcy of inserts on Dynamic row-length tables
consider setting 'concurrent_insert=2'."
Maybe one of those suggestions could help...
- Wade
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