Re: max_wal_senders

Hi,

On 2023-02-09 06:59:53 +0100, Laurenz Albe wrote:
> 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.

That's not *quite* true. The downsides are basically the same as for
max_connections (It's basically treated the same, see
InitializeMaxBackends()): You need more shared memory. There's a small
degradation of performance due to the increased size of some shared
datastructures, most prominently the lock table for heavyweight locks.

Greetings,

Andres Freund