Re: Synchronizing slots from primary to standby

On Thu, Jul 27, 2023 at 10:55 AM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>
> I wonder if we anyway some sort of design like this because we
> shouldn't allow to spawn as many workers as the number of databases.
> There has to be some existing or new GUC like max_sync_slot_workers
> which decided the number of workers.

It seems reasonable to not have one slot sync worker for each
database. IMV, the slot sync workers must be generic and independently
manageable - generic in the sense that given a database and primary
conninfo, each worker must sync all the slots related to the given
database, independently mangeable in the sense that separate GUC for
number of sync workers, launchable directly by logical replication
launcher dynamically. The work division amongst the sync workers can
be simple, the logical replication launcher builds a shared memory
structure based on number of slots to sync and starts the sync workers
dynamically, and each sync worker picks {dboid, slot name, conninfo}
from the shared memory, syncs it and proceeds with other slots.

Thoughts?

--
Bharath Rupireddy
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com