From: Tom Lane <tgl@sss.pgh.pa.us>
To: Tomas Vondra <tomas.vondra@enterprisedb.com>
cc: Amit Langote <amitlangote09@gmail.com>,
        "tsunakawa.takay@fujitsu.com" <tsunakawa.takay@fujitsu.com>,
        "Andrey V. Lepikhov" <a.lepikhov@postgrespro.ru>,
        Tomas Vondra <tomas.vondra@2ndquadrant.com>,
        "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Subject: Re: POC: postgres_fdw insert batching
In-reply-to: <261fbedb-1ced-82f7-e978-60cfe17bce07@enterprisedb.com>
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Comments: In-reply-to Tomas Vondra <tomas.vondra@enterprisedb.com>
	message dated "Thu, 21 Jan 2021 01:21:29 +0100"
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Date: Wed, 20 Jan 2021 20:22:57 -0500
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Tomas Vondra <tomas.vondra@enterprisedb.com> writes:
> I may be wrong, but the most likely explanation seems to be this is due 
> to the junk filter initialization, which simply moves past the end of 
> the mtstate->resultRelInfo array.

resultRelInfo is certainly pointing at garbage at that point.

> It kinda seems the GetForeignModifyBatchSize call should happen before 
> that block. The attached patch fixes this for me (i.e. regression tests 
> pass with no valgrind reports.

> Or did I get that wrong?

Don't we need to initialize ri_BatchSize for *each* resultrelinfo,
not merely the first one?  That is, this new code needs to be
somewhere inside a loop over the result rels.

			regards, tom lane