| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> |
| Cc: | Thom Brown <thom(at)linux(dot)com>, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>, Haribabu Kommi <kommi(dot)haribabu(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Parallel Seq Scan |
| Date: | 2015-11-13 05:26:28 |
| Message-ID: | CA+TgmoZtb3aBBoOX2rLBnTMWo1SLwsLp5hAPQkHapDEgHNzuBA@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Thu, Nov 12, 2015 at 10:39 PM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> The number of shared buffers hit could be different across different runs
> because the read sequence of parallel workers can't be guaranteed, also
> I don't think same is even guaranteed for Seq Scan node,
The number of hits could be different. However, it seems like any
sequential scan, parallel or not, should have a number of accesses
(hit + read) equal to the size of the relation. Not sure if that's
what is happening here.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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