Re: Asynchronous Append on postgres_fdw nodes.

From: Etsuro Fujita <etsuro(dot)fujita(at)gmail(dot)com>
To: Stephen Frost <sfrost(at)snowman(dot)net>
Cc: Kyotaro Horiguchi <horikyota(dot)ntt(at)gmail(dot)com>, Justin Pryzby <pryzby(at)telsasoft(dot)com>, Andrey Lepikhov <a(dot)lepikhov(at)postgrespro(dot)ru>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: Asynchronous Append on postgres_fdw nodes.
Date: 2021-05-16 14:39:14
Message-ID: CAPmGK16taCSD56k1cu9HptYBdJBQnWS4OUNQKnEvq=s_9k_Ntg@mail.gmail.com
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I'm resending this because I failed to reply to all.

On Sat, May 8, 2021 at 12:55 AM Etsuro Fujita <etsuro(dot)fujita(at)gmail(dot)com> wrote:
> On Fri, May 7, 2021 at 2:12 AM Stephen Frost <sfrost(at)snowman(dot)net> wrote:
> > In order to ensure that the data being returned from a foreign server
> > is consistent, postgres_fdw will only open one connection for a given
> > foreign server and will run all queries against that server sequentially
> > even if there are multiple foreign tables involved. In such a case, it
> > may be more performant to disable this option to eliminate the overhead
> > associated with running queries asynchronously.
>
> Ok, I’ll merge this into the next version.

Stephen’s version would be much better than mine, so I updated the
patch as proposed except the first sentence. If the foreign tables
are subject to different user mappings, multiple connections will be
opened, and queries will be performed in parallel. So I expanded the
sentence a little bit, to avoid misunderstanding. Attached is a new
version.

Best regards,
Etsuro Fujita

Attachment Content-Type Size
note-about-async-v2.patch application/octet-stream 988 bytes

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