[mythtv-users] Slow MySQL query after delete

crs23 pvr at groundhog.pair.com
Thu Sep 6 19:04:28 UTC 2007

> Hi crs, what speed is the processor in your machine (and what type etc.),
> as 
> my previous email showed, my old Athlon 2GHz (single core), with the 
> database running on a single SATA hard disk, could do ~15000 rows in
> ~14-15 
> sec, around 1000 rows a second, your data points are ~3000 rows in 30 sec, 
> around 100 rows a second. We should try and determine what could make your 
> database run at only 10% of the speed before throwing away rows.
> What was the OS, and did the mysql come as a pre-compiled package (I have 
> had issues with mysql before when compiled from source).
> Gareth 

It's a slow machine, a 600MHz C3.  It also has limited memory:  256MB. 
That's *easily* enough to record two programs and watch a third given the
hardware encoders and decoders.  It has a seagate barracuda drive that seems
plenty fast.  (That along with not needing a fan makes it a virtually
noiseless system.)

Don't be fooled by the 3000 rows returned.  From mysql-slow.log here's a
typical entry for this query:

# Query_time: 30  Lock_time: 0  Rows_sent: 3926  Rows_examined: 866966

That's 29k rows searched per second.  Sorry for not including this data
before but there's a lot of possibly useful information and I didn't want to
overload my original post.

MySQL is from KnoppMyth.  dpkg shows version 5.0.32-2.

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