[mythtv-users] Slow MySQL query after delete

crs23 pvr at groundhog.pair.com
Thu Sep 6 19:04:24 UTC 2007

Michael T. Dean wrote:
> Though ugly, the BUSQ (Big, Ugly Scheduler Query) seems to work (and
> scale) for everyone else using Myth, so unless you have a particularly
> large-scale setup (i.e. thousands of channels and hundreds/thousands of
> recording rules each generating multiple matches), it should work for
> you, too.  Can you provide specifics of your configuration (# of
> channels and #--and approximate type--of recording rules) so we can
> determine if the problem is actually a Myth issue before trying to fix
> the BUSQ (which, generally, no one ever wants to touch).

'BUSQ', I like that.

I have 81 channels and I have 87 rows in the record table.  Is the latter
the number of recording rules?  That's *way* more than I want.  Checking the
schedules page on MythWeb shows several rules, often identical, for many
programs.  This sounds like a problem.

Assuming that it is a problem I suspect how it may have happened.  MythTV
has not infrequently failed to record requested programs and recorded
unrequested programs for reasons unknown to me.  When that's happened I've
remove the magical new recording rules and added back the missing ones. 
Perhaps the missing ones were still there but somehow disabled?  I'll go
through the list and remove unwanted entries.

That said and again admiting to not being all that familiar with databases,
it's my understanding that a query that scales linearly with the size of the
database is not considered a good query.  When the DB has to scan every row
doesn't that suggest the need for an index?

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