Re: max_wal_senders

On Wed, 2023-02-08 at 18:07 -0500, Rick Otten wrote:
> I've been thinking about the max_wal_senders parameter lately and wondering 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 senders, it
will cause load.  A high limit is no problem as such.

> The documentation mentions an orphaned connection slot that may take a while to time out.
> How can I tell if I have any of those?  I was looking for a `pg_wal_slots` table
> similar to the `pg_replication_slots` table, but don't see anything obvious 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_keepalived_idle"
low enough so that the kernel will detect broken connections early on.

Yours,
Laurenz Albe