Re: Performance improvement for joins where outer side is unique

From: David Rowley <david(dot)rowley(at)2ndquadrant(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Performance improvement for joins where outer side is unique
Date: 2015-08-25 05:25:53
Message-ID: CAKJS1f8JCt15ngEP8sZO-JYYT8mS6HUP_CT0T6S_0ogk1kQt+Q@mail.gmail.com
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On 24 August 2015 at 14:29, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> David Rowley <david(dot)rowley(at)2ndquadrant(dot)com> writes:
> > I have to admit I don't much like it either, originally I had this as an
> > extra property that was only seen in EXPLAIN VERBOSE.
>
> Seems like a reasonable design from here.

The attached patch has the format in this way.

> (Note that for non-text output,
> I'd say the field should come out unconditionally. We only care about

abbreviating in text mode.)
>
>
If that's the case then why do we not enable verbose for all of the
non-text outputs?
It seems strange to start making exceptions on a case-by-case basis.

Regards

David Rowley

--
David Rowley http://www.2ndQuadrant.com/
<http://www.2ndquadrant.com/>
PostgreSQL Development, 24x7 Support, Training & Services

Attachment Content-Type Size
unique_joins_2015-08-25_feb3068.patch application/octet-stream 71.8 KB

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