Message-ID: <ba04a12d2b1e792e863e98cd88d3d54649464d21.camel@cybertec.at>
Subject: Re: max_wal_senders
From: Laurenz Albe <laurenz.albe@cybertec.at>
To: Rick Otten <rottenwindfish@gmail.com>, "pgsql-performa."
	 <pgsql-performance@postgresql.org>
Date: Thu, 09 Feb 2023 06:59:53 +0100
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On Wed, 2023-02-08 at 18:07 -0500, Rick Otten wrote:
> I've been thinking about the max_wal_senders parameter lately and wonderi=
ng if there
> is any harm in setting it too high.

No, there isn't, except that if you end up having too many *actual* WAL sen=
ders, it
will cause load.  A high limit is no problem as such.

> The documentation=C2=A0mentions an orphaned connection slot that may take=
 a while to time out.
> How can I tell if I have any of those?=C2=A0 I was looking for a `pg_wal_=
slots` table
> similar to the `pg_replication_slots` table, but don't see anything obvio=
us in the catalog.

The view is "pg_stat_replication", but you won't see there if an entry is
abandoned before PostgreSQL does and terminates it.  You can set "tcp_keepa=
lived_idle"
low enough so that the kernel will detect broken connections early on.

Yours,
Laurenz Albe