From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Robert Haas <robertmhaas@gmail.com>
Cc: Jeevan Chalke <jeevan.chalke@enterprisedb.com>
Cc: pgsql-hackers@lists.postgresql.org, David Rowley <david.rowley@2ndquadrant.com>
Subject: Re: Soon-to-be-broken regression test case
Date: Thu, 11 Oct 2018 13:39:52 -0300
Message-ID: <20181011163952.emtpcrzkpselhupj@alvherre.pgsql> (raw)
In-Reply-To: <5395.1539275668@sss.pgh.pa.us>
On 2018-Oct-11, Tom Lane wrote:
> I have been fooling around with a patch to allow pull-up of sub-selects
> that lack any FROM, along the lines discussed in
> https://www.postgresql.org/message-id/15944.1521127664@sss.pgh.pa.us
> I find that it is smart enough to reduce that EXISTS to a plain
> expression, yielding
>
> QUERY PLAN
> ----------------------------------------------------
> Subquery Scan on tenk1_vw_sec
> -> Index Only Scan using tenk1_unique1 on tenk1
> Index Cond: (unique1 = 0)
> (3 rows)
Hmm, I have the feeling that this would nullify some tests in
partition_prune also, which IIRC pretend to invoke runtime pruning with
things like "WHERE partcol = (select 1)".
--
Álvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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-hackers@postgresql.org
Cc: alvherre@2ndquadrant.com, tgl@sss.pgh.pa.us, robertmhaas@gmail.com, jeevan.chalke@enterprisedb.com, david.rowley@2ndquadrant.com
Subject: Re: Soon-to-be-broken regression test case
In-Reply-To: <20181011163952.emtpcrzkpselhupj@alvherre.pgsql>
* 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