[mythtv-users] Database tuning

[Simon Hobson]

David Watkins wrote:

> Simon Hobson <linux at thehobsons.co.uk> wrote:

>>So as far as I can tell, I've not got buffers large enough to hold indexes in memory,

Oops, that should say "I *have* got ..."

>You've probably thought about this already, but have you tried rationalising your recording rules.?

> When I looked at mine I found I had multiple rules for many programmes (including 20 different
> recording rules for the recording the Simpsons), accumulated over the years, plus dozens and dozens
> of rules for things I would never want to record again. Removing the unwanted stuff made a significant improvement to the rescheduling time.
There probably are a few I can take out, but not that many and I don't think there are many (if any) duplicated). Quite a few are marked as inactive which I assume should mean they require very little processing.

> I also removed a lot of stuff from 'Previously Recorded' that I knew I wouldn't want to record again. It meant losing my recording history but that wasn't a problem for me.

I was thinking that - but again, I don't think there's all that much - less than 9k old recordings. I do have heading of for 2k current recordings !

On the other hand, I have had a suggestion (off list) to try Schedules Direct who I hadn't realised until then have branched out and now cover UK. That would make it worth blowing away all the old recordings as nothing's going to match what I've been getting from Radio Times.

But still, if there's enough mamory to hold all the tables and indexes in memory, then I don't see why it appears to be creating 200+M of "something" on disk and creating a lot of wait I/O which seems to be my problem.

It also causes pauses in playback when recordings start and end - last night I had my iPad handy so was able to check - and each time a recording started or ended, there was a pause (several seconds) in playback. That'll be because the database (and OS) is on the same disks as the recordings (but not for long*) - however that's a symptom of the underlying problem rather than the problem itself.

* Ebuyer just had a too good to pass up deal on SSDs, so the OS and database will soon be on an SSD.