Re: Bypassing cursors in postgres_fdw to enable parallel plans

From: Alexander Pyhalov <a(dot)pyhalov(at)postgrespro(dot)ru>
To: Rafia Sabih <rafia(dot)pghackers(at)gmail(dot)com>
Cc: KENAN YILMAZ <kenan(dot)yilmaz(at)localus(dot)com(dot)tr>, Robert Haas <robertmhaas(at)gmail(dot)com>, Andy Fan <zhihuifan1213(at)163(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: Bypassing cursors in postgres_fdw to enable parallel plans
Date: 2025-12-17 14:09:28
Message-ID: e151c0a5ff43772f35dfceb1e041f333@postgrespro.ru
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Rafia Sabih писал(а) 2025-11-27 13:50:
> On Tue, 25 Nov 2025 at 15:24, KENAN YILMAZ
> <kenan(dot)yilmaz(at)localus(dot)com(dot)tr> wrote:
>
>> Hello Hackers,
>>
>> I have executed use_cursor = true/false with quick tests.
>>

Hi.

I've looked at this patch, because also was playing with tuplestore in
PgFdwScanState to have more predictable memory usage with large
fetch_size. Unfortunately, I've found that you can't use
TTSOpsMinimalTuple(?) tuplestore to store tuple's ctid. I hoped this
patch provides some solution for this issue, but no, it seems have the
same problem. Attaching test case with a reproducer.
--
Best regards,
Alexander Pyhalov,
Postgres Professional

Attachment Content-Type Size
selecting-ctids.diff text/x-diff 1.8 KB

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