| From: | Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> |
|---|---|
| To: | Sergei Kornilov <sk(at)zsrv(dot)org> |
| Cc: | Masahiko Sawada <masahiko(dot)sawada(at)2ndquadrant(dot)com>, Mahendra Singh <mahi6run(at)gmail(dot)com>, Dilip Kumar <dilipbalaut(at)gmail(dot)com>, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>, Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp>, Robert Haas <robertmhaas(at)gmail(dot)com>, Haribabu Kommi <kommi(dot)haribabu(at)gmail(dot)com>, Michael Paquier <michael(dot)paquier(at)gmail(dot)com>, Amit Langote <langote_amit_f8(at)lab(dot)ntt(dot)co(dot)jp>, David Steele <david(at)pgmasters(dot)net>, Claudio Freire <klaussfreire(at)gmail(dot)com>, Simon Riggs <simon(at)2ndquadrant(dot)com>, Pavan Deolasee <pavan(dot)deolasee(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: [HACKERS] Block level parallel vacuum |
| Date: | 2019-12-01 05:16:17 |
| Message-ID: | CAA4eK1LBv=i+RoyNU3cU4FA9eCLq1ARt5NRML76+r70vSX3U8g@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Sat, Nov 30, 2019 at 7:18 PM Sergei Kornilov <sk(at)zsrv(dot)org> wrote:
> Hello
>
> Its possible to change order of index processing by parallel leader? In
> v35 patchset I see following order:
> - start parallel processes
> - leader and parallel workers processed index lixt and possible skip some
> entries
> - after that parallel leader recheck index list and process the skipped
> indexes
> - WaitForParallelWorkersToFinish
>
> I think it would be better to:
> - start parallel processes
> - parallel leader goes through index list and process only indexes which
> are skip_parallel_index_vacuum = true
> - parallel workers processes indexes with skip_parallel_index_vacuum =
> false
> - parallel leader start participate with remainings parallel-safe index
> processing
> - WaitForParallelWorkersToFinish
>
> This would be less running time and better load balance across leader and
> workers in case of few non-parallel and few parallel indexes.
>
Why do you think so? I think the advantage of the current approach is that
once the parallel workers are launched, the leader can process indexes that
don't support parallelism. So, both type of indexes can be processed at
the same time.
--
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com
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