Skip site navigation (1) Skip section navigation (2)

Re: Using ctid column changes plan drastically

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Thomas Kellerer <spam_eater(at)gmx(dot)net>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Using ctid column changes plan drastically
Date: 2012-07-24 15:55:25
Message-ID: 22819.1343145325@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-performance
Thomas Kellerer <spam_eater(at)gmx(dot)net> writes:
> Tom Lane, 24.07.2012 16:23:
>> IIRC, type tid doesn't have any hash support.

> So the "bad" plan is expected?

Joins on tid columns just aren't supported very well at the moment.
Partly that's from lack of round tuits, and partly it's because it
doesn't seem all that wise to encourage people to use them.  There
are gotchas if any of the rows receive concurrent updates.

FWIW, it might be helpful to cast this as a NOT EXISTS rather than
NOT IN subquery.

			regards, tom lane

In response to

Responses

pgsql-performance by date

Next:From: Thomas KellererDate: 2012-07-24 16:32:09
Subject: Re: Using ctid column changes plan drastically
Previous:From: Maciek SakrejdaDate: 2012-07-24 15:50:42
Subject: Re: Geoserver-PostGIS performance problems

Privacy Policy | About PostgreSQL
Copyright © 1996-2014 The PostgreSQL Global Development Group