[mythtv-users] Very slow mythfrontend, mysql at 100%

Michael T. Dean mtdean at thirdcontact.com
Thu Nov 19 19:05:21 UTC 2009

On 11/19/2009 01:46 PM, Ronald Pijnacker wrote:
> 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


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