Horton

Re: psql's FETCH_COUNT (cursor) is not being respected for CTEs

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: "Daniel Verite" <daniel@manitou-mail.org>
Cc: Laurenz Albe <laurenz.albe@cybertec.at>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>, Robert Haas <robertmhaas@gmail.com>, Jakub Wartak <jakub.wartak@enterprisedb.com>
Date: 2024-04-02T20:13:23Z
Lists: pgsql-hackers 
"Daniel Verite" <daniel@manitou-mail.org> writes:
> 	Tom Lane wrote:
>> I do not buy that psql's FETCH_COUNT mode is a sufficient reason
>> to add it.  FETCH_COUNT mode is not something you'd use
>> non-interactively

> I should say that I've noticed significant latency improvements with
> FETCH_COUNT retrieving large resultsets, such that it would benefit
> non-interactive use cases.

Do you have a theory for why that is?  It's pretty counterintuitive
that it would help at all.

			regards, tom lane

Commits

  1. Further review for re-implementation of psql's FETCH_COUNT feature.

  2. Re-implement psql's FETCH_COUNT feature atop libpq's chunked mode.

  3. Support retrieval of results in chunks with libpq.

  4. Attempt to fix newly added Memoize regression test