| From: | Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> |
|---|---|
| To: | Jeff Davis <pgsql(at)j-davis(dot)com> |
| Cc: | Robert Haas <robertmhaas(at)gmail(dot)com>, Haribabu Kommi <kommi(dot)haribabu(at)gmail(dot)com>, Andres Freund <andres(at)2ndquadrant(dot)com>, Kouhei Kaigai <kaigai(at)ak(dot)jp(dot)nec(dot)com>, Amit Langote <amitlangote09(at)gmail(dot)com>, Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp>, Fabrízio Mello <fabriziomello(at)gmail(dot)com>, Thom Brown <thom(at)linux(dot)com>, Stephen Frost <sfrost(at)snowman(dot)net>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Parallel Seq Scan |
| Date: | 2015-07-01 10:07:09 |
| Message-ID: | CAA4eK1KUoOb8C8L-+bajLhBitePRRxGNZOjVFaVndsOR4tZNdA@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Wed, Jul 1, 2015 at 1:21 PM, Jeff Davis <pgsql(at)j-davis(dot)com> wrote:
>
> On Wed, 2015-07-01 at 11:07 +0530, Amit Kapila wrote:
>
> > For what you are asking to change name for?
>
> There are still some places, at least in the comments, that call it a
> parallel sequential scan.
>
In the initial version of patch, there was only one node parallel seqscan
node and the occurrences you are seeing are left over's, I will change
them in next patch.
>
> > a. Infrastructure for parallel execution, like some of the stuff in
> > execparallel.c, heapam.c,tqueue.c, etc and all other generic
> > (non-nodes specific) code.
>
> Did you consider passing tuples through the tqueue by reference rather
> than copying? The page should be pinned by the worker process, but
> perhaps that's a bad assumption to make?
>
Yes, IIRC there was some discussion happened and I haven't used for
the reason you mentioned. It doesn't same sane to hold the pin on
page for long time (we need to retain the pin till master backend processes
that tuple).
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com
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