Horton

Re: Small memory fixes for pg_createsubcriber

Michael Paquier <michael@paquier.xyz>

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From: Michael Paquier <michael@paquier.xyz>
To: Euler Taveira <euler@eulerto.com>
Cc: "ranier.vf@gmail.com" <ranier.vf@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2025-02-12T03:53:51Z
Lists: pgsql-hackers 
On Tue, Feb 11, 2025 at 01:32:32PM -0300, Euler Taveira wrote:
> There is no bug. They are the same behind the scenes. I'm fine changing it. It
> is a new code and it wouldn't cause a lot of pain to backpatch patches in the
> future.

On consistency grounds, and as this is documented in fe-exec.c at the
top of PQfreemem(), I can get behind the switch.

> Even if the pg_createsubscriber aims to run in a small amount of time, hence,
> it is fine to leak memory, the initial commit cleaned up all variables but a
> subsequent commit 4867f8a555c apparently didn't. Although it is just a low
> impact improvement, it is better to be strict and shut up SASTs.

check_and_drop_existing_subscriptions() is called once per database in
setup_subscriber(), and we are not going to have millions of them in
this list.  We don't usually care for such short-lived things, but as
the original commit did the effort in d44032d01463, I don't see why we
cannot do it here, either.
--
Michael

Commits

  1. pg_upgrade: Fix inconsistency in memory freeing

  2. pg_amcheck: Fix inconsistency in memory freeing

  3. Fix some inconsistencies with memory freeing in pg_createsubscriber

  4. Drop pre-existing subscriptions from the converted subscriber.