Horton

Re: Design of pg_stat_subscription_workers vs pgstats

Andres Freund <andres@anarazel.de>

View thread View on postgr.es
From: Andres Freund <andres@anarazel.de>
To: Masahiko Sawada <sawada.mshk@gmail.com>
Cc: "David G. Johnston" <david.g.johnston@gmail.com>, Amit Kapila <amit.kapila16@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2022-02-15T16:26:02Z
Lists: pgsql-hackers 
Hi,

On 2022-02-03 14:35:10 +0900, Masahiko Sawada wrote:
> Yes, but if we use shmem IPC, we need to allocate shared memory for
> them based on the number of subscriptions, not logical replication
> workers (i.e., max_logical_replication_workers). So we cannot estimate
> memory in the beginning. Also, IIUC the number of subscriptions that
> are concurrently working is limited by max_replication_slots (see
> ReplicationStateCtl) but I think we need to remember the state of
> disabled subscriptions too.

Use dshash (i.e. dsm) with a small initial allocation in non-dynamic shared
memory...

Greetings,

Andres Freund

Commits

  1. Reconsider pg_stat_subscription_workers view.

  2. Add a view to show the stats of subscription workers.