Re: Optimization for updating foreign tables in Postgres FDW

From: Rushabh Lathia <rushabh(dot)lathia(at)gmail(dot)com>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Etsuro Fujita <fujita(dot)etsuro(at)lab(dot)ntt(dot)co(dot)jp>, Noah Misch <noah(at)leadboat(dot)com>, Michael Paquier <michael(dot)paquier(at)gmail(dot)com>, Thom Brown <thom(at)linux(dot)com>, Stephen Frost <sfrost(at)snowman(dot)net>, Albe Laurenz <laurenz(dot)albe(at)wien(dot)gv(dot)at>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Shigeru Hanada <shigeru(dot)hanada(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Optimization for updating foreign tables in Postgres FDW
Date: 2016-04-08 13:21:23
Message-ID: CAGPqQf2590+ojTPehMXbJGCKYQoWBRcHCsATpktcHhGuyzFU_w@mail.gmail.com
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On Fri, Apr 8, 2016 at 6:28 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:

> On Fri, Apr 8, 2016 at 3:05 AM, Etsuro Fujita
> <fujita(dot)etsuro(at)lab(dot)ntt(dot)co(dot)jp> wrote:
> >> What do you think? This open item's seven-day deadline has passed. It
> >> would
> >> help keep things moving to know whether you consider your latest patch
> >> optimal
> >> or whether you wish to change it the way Michael described.
> >
> > I wish to change it that way because it not only avoids the duplicate but
> > fixes a bug in the previous patch that I overlooked that there is a race
> > condition if a signal arrives just before entering the CheckSocket.
> >
> > Attached is an updated version of the patch.
>
> The comment just before the second hunk in the patch says:
>
> * We don't use a PG_TRY block here, so be careful not to throw error
> * without releasing the PGresult.
>
> But the patch adds a whole bunch of new things there that seem like
> they can error out, like CHECK_FOR_INTERRUPTS(), for example. Isn't
> that a problem?
>

Basically we fetching the PGresult, after the newly added hunk, so there
should not be any problem.

But yes comment is definitely at wrong place.

PFA patch with correction.

>
>
--
> Robert Haas
> EnterpriseDB: http://www.enterprisedb.com
> The Enterprise PostgreSQL Company
>

--
Rushabh Lathia

Attachment Content-Type Size
pgfdw-direct-modify-v3.patch application/x-patch 3.4 KB

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