[mythtv-users] Very slow mythfrontend, mysql at 100%
pijnacker at dse.nl
Fri Nov 20 14:00:16 UTC 2009
>> My primary frontend is very slow since a while.
>> Deleting recordings etc. is taking seconds, which is very annoying.
>> I noticed that mysql is at 100% cpu on the backend.
>> Could it be that over the years mythconverg has become so big that
>> this is the cause of the issue?
>> If so, which tables can I safely purge?
> No, MythTV cleans up the data in the mythconverg database--and besides,
> myth doesn't use that much data, so even if stuff wasn't being cleaned up,
> it wouldn't get that large.
> Something else is going on.
> I have a clean mythconverg database and get:
> # du -sh /srv/mysql/mythconverg/
> 448M /srv/mysql/mythconverg/
> (that's 448MiB). That's not very big from a MySQL standpoint but is
> probably rather large from a mythconverg standpoint. My performance is
> fine, though.
> I'd guess it's more likely schema corruption (i.e. missing/broken indices,
> etc.--and, yes, I saw that you said in IRC it's not crashed tables, but I
> mean broken schema) or something.
> If you'd like to get Myth to recreate your schema (and all indices, etc.)
> see http://www.mythtv.org/wiki/Database_Backup_and_Restore and:
> a) Back up your DB
> b) Drop your DB
> c) Create a new DB with mc.sql
> d) Create a new DB schema by running and exiting mythtv-setup
> e) Do a partial restore (
> f) Run mythtv-setup to reconfigure mythbackend
> g) Start mythbackend
> h) Run mythfrontend and reconfigure mythfrontend and all your plugins
Since the wiki page discourages partial restores and I wasn't in the mood
to reconfigure my systems, I tried just doing a backup/restore.
I compared the first backup with a second (after restore) with identical results.
But still somehow this managed to make the problem go away!
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