[mythtv-users] Slow MySQL query after delete
ross camm
rossco at whyza.net
Thu Nov 29 01:22:58 UTC 2007
do you have many rows in recordedseek ?
i do, nearly 1.5 million rows, and converting from MyISAM to InnoDB for
the recordedseek table reduced my query time from 20-30 secs down to 2-3
secs or less.
as such deletions are now nearly instant.
On Wed, 2007-11-28 at 20:16 -0500, Larry K wrote:
> I am also having trouble with the BUSQ when I delete recordings, with
> query times no better than 7-8 seconds. This is on an Athlon 2500+
> with 512MB ram. Myth 0.20 and MySQL 5.0.37, I think. Before I
> upgraded to 0.20, I was running 0.18 and this problem did not exist
> for me. I'm guessing this BUSQ was introduced after 0.18.
>
> I cleaned up my recording schedules to eliminate duplicate schedules
> (there were a few), and I also tried to avoid schedules on 'any
> channel'. I currently have 4,800 rows in oldrecorded, 550 rows in
> recordmatch, and 100 rows in record. None of this seems excessive to
> me. I also optimized my database, and it still takes 6-7 seconds to
> run this query.
>
> I wonder if 6-7 seconds is as good as it gets for me? Have I hit the
> wall? Can anyone with a config similar to mine get this query to run
> in say 1 second?
>
> /etc/my.conf:
>
> [mysqld]
> datadir=/var/lib/mysql
> socket=/var/lib/mysql/mysql.sock
> key_buffer = 16M
> table_cache = 128
> sort_buffer_size = 2M
> myisam_sort_buffer_size = 8M
> query_cache_size = 16M
> log_slow_queries=/var/log/slowsql.log
> long_query_time=5
>
> [mysql.server]
> user=mysql
> basedir=/var/lib
>
> [safe_mysqld]
> err-log=/var/log/mysqld.log
> pid-file=/var/run/mysqld/mysqld.pid
>
>
>
> On 11/24/07, crs23 <pvr at groundhog.pair.com> wrote:
>
> I used MythWeb to both discover duplicates by inspection and
> delete them.
> That took a long time because of the very problem I was trying
> to fix but
> each deletion went faster than the last as the query got
> faster and faster.
> A way to delete multiple recordings or recording rules at once
> would be nice
> but I wasn't about to try deleting records directly from the
> database
> because I don't know if that would cause some kind of
> inconsistency between
> tables.
>
>
> Larry K wrote:
> >
> > What was your method to determine the duplicates? And did
> you simply
> > issue
> > a SQL delete to get rid of them, or some other mechanism?
> >
> > On 9/6/07, crs23 < pvr at groundhog.pair.com> wrote:
> >>
> >>
> >>
> >> Michael T. Dean wrote:
> >> >
> >> > I don't think much testing has been done on systems
> having identical
> >> > recording rules. Though it shouldn't cause issues,
> cleaning out the
> >> > duplicates (triplicates? whatever) would significantly
> simplify the
> >> > query's processing, so doing so would be very much to
> your advantage.
> >> >
> >>
> >> Done and the improvement was substantial. There were
> several multiple
> >> entries. One program had about a dozen duplicate entries
> and that just
> >> happened to be the program with the most previously
> recorded episodes. I
> >> also changed the recordings to be on a particular channel
> instead of any
> >> channel which I think helped to.
> >>
> >> I'm now down to ~150,000 rows examined in 5.5 seconds, 696
> rows
> >> returned. 5
> >> or 6 seconds is hugely better but still a bit of an
> annoyance. But I'm
> >> very
> >> pleased with the results so far and the incredible support
> I've received
> >> on
> >> this forum. Thank you to everyone!
> >>
> >> --
> >> View this message in context:
> >>
> http://www.nabble.com/Slow-MySQL-query-after-delete-tf4366877s15552.html#a12534738
> >> Sent from the mythtv-users mailing list archive at
> Nabble.com.
> >>
> >> _______________________________________________
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>
> --
> View this message in context:
> http://www.nabble.com/Slow-MySQL-query-after-delete-tf4366877s15552.html#a13926650
> Sent from the mythtv-users mailing list archive at Nabble.com.
>
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