Re: parallel append vs. simple UNION ALL

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Rajkumar Raghuwanshi <rajkumar(dot)raghuwanshi(at)enterprisedb(dot)com>
Cc: "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Andres Freund <andres(at)anarazel(dot)de>
Subject: Re: parallel append vs. simple UNION ALL
Date: 2018-03-07 18:57:18
Message-ID: CA+Tgmoaob_Strkg4Dcx=VyxnyXtrmkV=ofj=pX7gH9hSre-g0Q@mail.gmail.com
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On Wed, Mar 7, 2018 at 5:36 AM, Rajkumar Raghuwanshi
<rajkumar(dot)raghuwanshi(at)enterprisedb(dot)com> wrote:
> With 0001 applied on PG-head, I got reference leak warning and later a
> server crash.
> this crash is reproducible with enable_parallel_append=off also.
> below is the test case to reproduce this.

New patches attached, fixing all 3 of the issues you reported:

0001 is a new patch to fix the incorrect parallel safety marks on
upper relations. I don't know of a visible effect of this patch by
itself, but there might be one.

0002 is the same as the old 0001, but I made a fix in
SS_charge_for_initplans() which fixed your most recent crash report.
Either this or the previous change also fixed the crash you saw when
using tab-completion. Also, I added some test cases based on your
failing examples.

0003-0005 are the same as the old 0002-0004.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

Attachment Content-Type Size
0005-Consider-Parallel-Append-as-a-way-to-implement-a-uni.patch application/octet-stream 5.0 KB
0004-Generate-a-separate-upper-relation-for-each-stage-of.patch application/octet-stream 20.6 KB
0003-Rewrite-recurse_union_children-to-iterate-rather-tha.patch application/octet-stream 5.7 KB
0002-Let-Parallel-Append-over-simple-UNION-ALL-have-parti.patch application/octet-stream 9.3 KB
0001-Correctly-assess-parallel-safety-of-tlists-when-SRFs.patch application/octet-stream 8.8 KB

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