Re: Custom table AMs need to include heapam.h because of BulkInsertState

From: Andres Freund <andres(at)anarazel(dot)de>
To: David Rowley <david(dot)rowley(at)2ndquadrant(dot)com>
Cc: Michael Paquier <michael(at)paquier(dot)xyz>, Robert Haas <robertmhaas(at)gmail(dot)com>, Postgres hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: Custom table AMs need to include heapam.h because of BulkInsertState
Date: 2019-07-17 23:36:11
Message-ID: 20190717233611.h3gpcj4yypymmsax@alap3.anarazel.de
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Hi,

On 2019-07-18 11:29:37 +1200, David Rowley wrote:
> On Wed, 17 Jul 2019 at 06:46, Andres Freund <andres(at)anarazel(dot)de> wrote:
> > 1) Have ExecFindPartition() return via a bool* whether the partition is
> > being accessed for the first time. In copy.c push the partition onto
> > a list of to-be-bulk-finished tables.
> > 2) Add a execPartition.c function that returns all the used tables from
> > a PartitionTupleRouting*.
>
> #2 seems better than #1 as it does not add overhead to ExecFindPartition().

I don't see how #1 would add meaningful overhead compared to the other
costs of that function. Wouldn't it just be adding if (isnew) *isnew =
false; to the "/* ResultRelInfo already built */" branch, and the
reverse to the else? That got to be several orders of magnitude cheaper
than e.g. FormPartitionKeyDatum() which is unconditionally executed?

> Are you thinking this should go back into v12, or just for v13 only?

Not sure, tbh. Probably depends a bit on how complicated it'd look?

Greetings,

Andres Freund

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