| From: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Robert Haas <robertmhaas(at)gmail(dot)com>, Jeevan Chalke <jeevan(dot)chalke(at)enterprisedb(dot)com>, pgsql-hackers(at)lists(dot)postgresql(dot)org, David Rowley <david(dot)rowley(at)2ndquadrant(dot)com> |
| Subject: | Re: Soon-to-be-broken regression test case |
| Date: | 2018-10-11 16:39:52 |
| Message-ID: | 20181011163952.emtpcrzkpselhupj@alvherre.pgsql |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
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
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Tom Lane | 2018-10-11 16:45:24 | Re: Soon-to-be-broken regression test case |
| Previous Message | Tom Lane | 2018-10-11 16:34:28 | Soon-to-be-broken regression test case |