Re: release notes: tids & self-joins

On Thu, Jun 13, 2019 at 01:22:16PM -0400, Tom Lane wrote:
> Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> > The release notes say:
> > <listitem>
> > <!--
> > Author: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
> > 2018-12-30 [b5415e3c2] Support parameterized TidPaths.
> > Author: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
> > 2018-12-30 [0a6ea4001] Add a hash opclass for type "tid".
> > -->
>
> > <para>
> > Improve optimization of self-joins (Tom Lane)
> > </para>
> > </listitem>
>
> > I don't think that's an accurate summary of those two items. It's
> > true that they could make self-joins more efficient, but my reading is
> > that it would only do so if the self-join happened to use the ctid
> > column.
>
> Yeah. I think Bruce misread the commit messages, which commented that
> joining on TID is only likely to be useful in a self-join.
>
> > So I think that this should probably be changed to say something like
> > "Improve optimization of self-joins on ctid columns" or "Improve
> > optimization of joins involving columns of type tid."
>
> The latter seems fine to me.

I have updated to use the later wording.

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

+ As you are, so once was I. As I am, so you will be. +
+ Ancient Roman grave inscription +