Re: 7k records into Sort node, 4.5m out?

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Christophe Pettus <xof(at)thebuild(dot)com>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: 7k records into Sort node, 4.5m out?
Date: 2012-08-15 20:51:12
Message-ID: 16268.1345063872@sss.pgh.pa.us
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-performance

Christophe Pettus <xof(at)thebuild(dot)com> writes:
> On Aug 13, 2012, at 7:11 PM, Tom Lane wrote:
>> The whole thing looks a bit weird to me --- why did it not use a
>> nestloop join with inner indexscan on charlie? With 7000 rows on the
>> other side, the estimated cost for that shouldn't have been more than
>> about 30000 ...

> Here's the same query with set enable_megejoin = off. All of the other query tuning parameters are default.

> http://explain.depesz.com/s/dqO

Maybe you had better show us the actual query, and the table/index
definitions. Because it's sure making odd choices here. This seems
like the wrong join order altogether ...

regards, tom lane

In response to

Responses

Browse pgsql-performance by date

  From Date Subject
Next Message Josh Berkus 2012-08-15 21:02:35 Re: 7k records into Sort node, 4.5m out?
Previous Message Christophe Pettus 2012-08-15 19:13:19 Re: 7k records into Sort node, 4.5m out?