Horton

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

Daniel Verite <daniel@manitou-mail.org>

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From: "Daniel Verite" <daniel@manitou-mail.org>
To: "Tom Lane" <tgl@sss.pgh.pa.us>
Cc: PostgreSQL Hackers <pgsql-hackers@postgresql.org>, Robert Haas <robertmhaas@gmail.com>, Jakub Wartak <jakub.wartak@enterprisedb.com>
Date: 2023-07-07T17:42:57Z
Lists: pgsql-hackers

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	Tom Lane wrote:

> This gives me several "-Wincompatible-pointer-types" warnings
> [...]
> I think what you probably ought to do to avoid all that is to change
> the arguments of PrintQueryResult and nearby routines to be "const
> PGresult *result" not just "PGresult *result".

The const-ness issue that I ignored in the previous patch is that
while C is fine with passing T* to a function expecting const T*, it's
not okay with passing T** to a function expecting const T**,
or more generally converting T** to const T**.

When callers need to pass arrays of PGresult* instead of const
PGresult*, I've opted to remove the const qualifiers for the functions
that are concerned by this change.


PFA an updated patch.


Best regards,
-- 
Daniel Vérité
https://postgresql.verite.pro/
Twitter: @DanielVerite

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