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: 2017-01-19 12:07:19
Message-ID: CAOGQiiOcRh=wVsHWfPTOqmpGLU-Q0zc5YQH8MiQ+9AzJZRuK8g@mail.gmail.com
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On Fri, Jan 13, 2017 at 2:19 PM, Rafia Sabih
<rafia(dot)sabih(at)enterprisedb(dot)com> wrote:
> 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.
>

Please find the attached file rebased patch of parallel index-only
scan on the latest Parallel index-scan patch [1].

[1] https://www.postgresql.org/message-id/CAA4eK1L-gb0Fum3mQN4c5PWJXNE7xs7pzwMDWsrDYLucKqvJ2A%40mail.gmail.com
--
Regards,
Rafia Sabih
EnterpriseDB: http://www.enterprisedb.com/

Attachment Content-Type Size
parallel_index_only_v5.patch application/octet-stream 11.0 KB

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