[mythtv-users] Bad mysql performance -- huge oldrecorded -- joins without index

John Veness John.Veness.mythtv at pelago.org.uk
Wed Jun 8 14:18:19 UTC 2016

On 08/06/2016 14:55, Michael T. Dean wrote:
> So, let's think about the number you had.  If you record 27 shows 
> every day of every year, it would still take you more than 10 years to 
> get 100k entries in your recording history.  Most people don't record 
> anywhere near 27 shows per day, let alone every day (especially in 
> mid-season/summer season/...).

I'm not the OP, but I was interested in the "how many shows per day" 
people record. Before I had kids I probably recorded only a couple of 
shows per day, but more recently I probably record 20 or so, the 
majority of which never get watched.

Specifically, I have dozens of recording rules to record the series that 
they are interested in. Each rule is set to keep maximum 10 episodes, 
deleting the oldest when the maximum is reached, and I set it to only 
match duplicates in current recordings (unlike most of my recording 
rules for the grown-ups, which look for duplicates in current and 
previous recordings and have no limit).

That way, at any one time, they have the 10 most recent episodes 
broadcast for a whole load of different shows, from which they watch 
freely. They don't need to bother to delete and the selection will 
freshen over time. The selection they get is similar to what can be 
streamed on demand, without taking up my Internet bandwidth. These are 
shows with no continuing storyline, so order doesn't matter, and they 
don't mind watching episodes they've watched before, in fact they love 
to do so!

I haven't looked in my oldrecorded table recently, but I expect the 
above behaviour is causing it to grow considerably since adding all 
these rules. For episodes that have been recorded multiple times, will 
it be storing multiple rows in oldrecorded?


John Veness, MythTV user, UK, DVB-T

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