Re: Performance improvement for joins where outer side is unique

From: David Rowley <david(dot)rowley(at)2ndquadrant(dot)com>
To: Simon Riggs <simon(at)2ndquadrant(dot)com>
Cc: Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Performance improvement for joins where outer side is unique
Date: 2015-12-17 13:17:20
Message-ID: CAKJS1f8MpcL4_oS+n-vmnisd_8OMuZR2vyLETOF7ABSLk_iNZg@mail.gmail.com
Views: Raw Message | Whole Thread | Download mbox
Thread:
Lists: pgsql-hackers

On 17 December 2015 at 19:11, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:

> On 17 December 2015 at 00:17, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>
> wrote:
>
>> I'd go with match_first_tuple_only.
>
>
> +1
>
> unique_inner is a state that has been detected, match_first_tuple_only is
> the action we take as a result.
>
>
Ok great. I've made it so in the attached. This means the comment in the
join code where we perform the skip can be a bit less verbose and all the
details can go in where we're actually setting the match_first_tuple_only
to true.

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

Attachment Content-Type Size
unique_joins_18-12-2015_843fb71.patch application/octet-stream 76.2 KB

In response to

Responses

Browse pgsql-hackers by date

  From Date Subject
Next Message Fabien COELHO 2015-12-17 13:33:12 Re: extend pgbench expressions with functions
Previous Message David Rowley 2015-12-17 12:28:56 Re: Combining Aggregates