From: Tom Lane <tgl@sss.pgh.pa.us>
To: Jake Magner <jakemagner90@gmail.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Merge Join chooses very slow index scan
Date: Thu, 19 Mar 2015 10:58:26 -0400
Message-ID: <31348.1426777106@sss.pgh.pa.us> (raw)
In-Reply-To: <30571.1426775332@sss.pgh.pa.us>
References: <1426746214298-5842523.post@n5.nabble.com>
<30571.1426775332@sss.pgh.pa.us>
List-Unsubscribe: <mailto:majordomo@postgresql.org?body=unsub%20pgsql-performance>
I wrote:
> [ assorted possible workarounds ]
Actually, an easy fix might be to create a 2-column index on
usagestats(type, tid). I think the planner should be able to
use that to produce sorted output for the mergejoin, and you'd
get the best of both worlds, because the indexscan will stop
immediately when it's exhausted the rows with type = 'vehicle'.
regards, tom lane
--
Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-performance
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, jakemagner90@gmail.com
Subject: Re: Merge Join chooses very slow index scan
In-Reply-To: <31348.1426777106@sss.pgh.pa.us>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox