Re: Message queue table..

[Jesper Krogh <jesper(at)krogh(dot)cc>]

Craig Ringer wrote:
> Jesper Krogh wrote:
> > Hi.
> >
> > I have this "message queue" table.. currently with 8m+ records. 
> > Picking the top priority messages seem to take quite long.. it is just 
> > a matter of searching the index.. (just as explain analyze tells me it 
> > does).
> >
> > Can anyone digest further optimizations out of this output? (All 
> > records have funcid=4)
>
> You mean all records of interest, right, not all records in the table?

Actually all the records.. since all the other virtual queues currently 
are empty.

> What indexes do you have in place? What's the schema? Can you post a "\d 
> tablename" from psql?
>
> > # explain analyze SELECT job.jobid, job.funcid, job.arg, job.uniqkey, 
> > job.insert_time, job.run_after, job.grabbed_until, job.priority, 
> > job.coalesce FROM workqueue.job  WHERE (job.funcid = 4) AND 
> > (job.run_after <= 1208442668) AND (job.grabbed_until <= 1208442668) 
> > AND (job.coalesce = 'Efam') ORDER BY funcid, priority ASC LIMIT 1

I found that removing the funcid from the order by made it use a better 
index. (priority, run_after, grabbed_until)  that probably makes sense 
since the funcid doesnt give any value in the index at all.

thanks for leading me back on track.

Jesper

--
Jesper