Re: Parallel Index-only scan

From: Rafia Sabih <rafia(dot)sabih(at)enterprisedb(dot)com>
To: Rahila Syed <rahilasyed90(at)gmail(dot)com>
Cc: Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Parallel Index-only scan
Date: 2017-01-13 08:49:07
Message-ID: CAOGQiiM4kxtUDp+ODJKqX0z9wxRATT=vfRpjSbQc4yv7c2mMVA@mail.gmail.com
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On Thu, Jan 12, 2017 at 5:39 PM, Rahila Syed <rahilasyed90(at)gmail(dot)com> wrote:
> Hello,
>
> On applying the patch on latest master branch and running regression tests
> following failure occurs.
> I applied it on latest parallel index scan patches as given in the link
> above.
>
> ***
> /home/rahila/postgres/postgres/src/test/regress/expected/select_parallel.out
> 2017-01-03 14:06:29.122022780 +0530
> ---
> /home/rahila/postgres/postgres/src/test/regress/results/select_parallel.out
> 2017-01-12 14:35:56.652712622 +0530
> ***************
> *** 92,103 ****
> explain (costs off)
> select sum(parallel_restricted(unique1)) from tenk1
> group by(parallel_restricted(unique1));
> ! QUERY PLAN
> ! ----------------------------------------------------
> HashAggregate
> Group Key: parallel_restricted(unique1)
> ! -> Index Only Scan using tenk1_unique1 on tenk1
> ! (3 rows)
>
> set force_parallel_mode=1;
> explain (costs off)
> --- 92,105 ----
> explain (costs off)
> select sum(parallel_restricted(unique1)) from tenk1
> group by(parallel_restricted(unique1));
> ! QUERY PLAN
> ! -------------------------------------------------------------------
> HashAggregate
> Group Key: parallel_restricted(unique1)
> ! -> Gather
> ! Workers Planned: 4
> ! -> Parallel Index Only Scan using tenk1_unique1 on tenk1
> ! (5 rows)
>
> IIUC, parallel operation being performed here is fine as parallel restricted
> function occurs above Gather node
> and just the expected output needs to be changed.
>

True, fixed it, please find the attached file for the latest version.

> Thank you,
> Rahila Syed
>
Thanks a lot for the review Rahila.
--
Regards,
Rafia Sabih
EnterpriseDB: http://www.enterprisedb.com/

Attachment Content-Type Size
parallel_index_only_v4.patch application/octet-stream 9.8 KB

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