[mythtv-users] Duplicate detection

[Jan Ceuleers]

On 24/09/16 11:56, Mike Perkins wrote:
> A note that may help - if you're linking tables then it might be worth
> setting up temporary indexes on the fields used for joins (assuming they
> don't already have them). This should make a BIG difference to the
> amount of processing required.

The kinds of explosive resource usage I noticed previously was memory,
not CPU. This was probably because of the subquery I'd included in the
WHERE clause in my previous attempts at solving this. 't Was an increase
by several gigabytes in the space of a few seconds, which brought the
machine to its knees and caused the OOM killer to kick in.

The queries I posted today execute pretty much instantaneously on my
system, but of course I don't know how mythtv incorporates them into the
scheduler query, which is why I asked for more details.

But still, for my understanding: I would expect an index to trade
reduced CPU usage for increased memory and disk usage, is that right? If
so that might not necessarily be a good idea on my system which has a
total of 6GB of virtual memory (which is RAM+swap) of which just over
2GB is in use while the system is idle (so just under 4GB headroom half
of which is swap).

Thx, Jan