Re: asynchronous execution

From: Antonin Houska <ah(at)cybertec(dot)at>
To: Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: asynchronous execution
Date: 2017-06-28 08:23:54
Message-ID: 4579.1498638234@localhost
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Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp> wrote:

> The patch got conflicted. This is a new version just rebased to
> the current master. Furtuer amendment will be taken later.

Can you please explain this part of make_append() ?

/* Currently async on partitioned tables is not available */
Assert(nasyncplans == 0 || partitioned_rels == NIL);

I don't think the output of Append plan is supposed to be ordered even if the
underlying relation is partitioned. Besides ordering, is there any other
reason not to use the asynchronous execution?

And even if there was some, the planner should ensure that executor does not
fire the assertion statement above. The script attached shows an example how
to cause the assertion failure.

--
Antonin Houska
Cybertec Schönig & Schönig GmbH
Gröhrmühlgasse 26
A-2700 Wiener Neustadt
Web: http://www.postgresql-support.de, http://www.cybertec.at

Attachment Content-Type Size
async_append_test.sh text/plain 1.7 KB

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