Re: Performance trouble finding records through related records

From: sverhagen <sverhagen(at)wps-nl(dot)com>
To: pgsql-performance(at)postgresql(dot)org
Subject: Re: Performance trouble finding records through related records
Date: 2011-03-03 00:12:36
Message-ID: 1299111156142-3407330.post@n5.nabble.com
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Thanks for your help already!
Hope you're up for some more :-)

Andy Colson wrote:
>
> First off, excellent detail.
>
> Second, your explain analyze was hard to read... but since you are not
> really interested in your posted query, I wont worry about looking at
> it... but... have you seen:
>
> http://explain.depesz.com/
>

Thanks for that. Using it below :-)

Andy Colson wrote:
>
> If you run the individual queries, without the union, are the part's slow
> too?
>

Only problem is the second part. So that part can safely be isolated. Also
the following does not play a role at this point: WHERE events2.eventtype_id
IN
(100,103,105,...

Then I went ahead and denormalized the transactionId on both ends, so that
both events_events records and events_eventdetails records have the
transactionId (or NULL). That simplifies the query to this:

SELECT events_events.* FROM events_events WHERE transactionid IN (
SELECT transactionid FROM events_eventdetails customerDetails
WHERE customerDetails.keyname='customer_id'
AND substring(customerDetails.value,0,32)='1957'
AND transactionid IS NOT NULL
) ORDER BY id LIMIT 50;

To no avail. Also changing the above WHERE IN into implicit/explicit JOIN's
doesn't make more than a marginal difference. Should joining not be very
efficient somehow?

http://explain.depesz.com/s/Pnb

The above link nicely shows the hotspots, but I am at a loss now as how to
approach them.

Andy Colson wrote:
>
> Looked like your row counts (the estimate vs the actual) were way off,
> have you analyzed lately?
>

Note sure what that means.
Isn't all the maintenance nicely automated through my config?

Andy Colson wrote:
>
> I could not tell from the explain analyze if an index was used, but I
> notice you have a ton of indexes on events_events table.
>

Yes, a ton of indexes, but still not the right one :-)

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