| From: | Andres Freund <andres(at)anarazel(dot)de> |
|---|---|
| To: | Laurenz Albe <laurenz(dot)albe(at)cybertec(dot)at> |
| Cc: | Rick Otten <rottenwindfish(at)gmail(dot)com>, "pgsql-performa(dot)" <pgsql-performance(at)postgresql(dot)org> |
| Subject: | Re: max_wal_senders |
| Date: | 2023-02-09 06:40:12 |
| Message-ID: | 20230209064012.4txdzjzp2rkkms66@awork3.anarazel.de |
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| Lists: | pgsql-performance |
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
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