[mythtv-commits] Ticket #12451: Playback start taking ages due to slow loading of the seek table from a heavily fragmented MyISAM table

[MythTV]

#12451: Playback start taking ages due to slow loading of the seek table from a
heavily fragmented MyISAM table
----------------------------------+-------------------------
     Reporter:  dekarl            |      Owner:
         Type:  Patch - Feature   |     Status:  new
     Priority:  minor             |  Milestone:  unknown
    Component:  MythTV - General  |    Version:  Unspecified
     Severity:  medium            |   Keywords:
Ticket locked:  0                 |
----------------------------------+-------------------------
 http://www.psce.com/blog/2012/07/09/data-fragmentation-problem-in-mysql-
 myisam/
 hints that fragmented MyISAM tables can have very bad performance once the
 table gets to big for the memory caches.
 On a backend that records and deletes recordings this will happen to the
 seek table.
 There is a statement for live defragmentation on a running system (even in
 parallel to recordings)
 {{{
 ALTER TABLE recordedseek ORDER BY chanid, starttime;
 }}}
 attached is a proof of concept patch that adds the defragmentation to the
 daily database maintenance job after the removal of stale entries in the
 recordedseek table. As the query runs more then four minutes on my backend
 I'd prefer some testing by others before I commit this as is.

--
Ticket URL: <https://code.mythtv.org/trac/ticket/12451>
MythTV <http://www.mythtv.org>
MythTV Media Center