Re: Synchronizing slots from primary to standby

On Fri, Jul 28, 2023 at 8:54 PM Bharath Rupireddy
<bharath(dot)rupireddyforpostgres(at)gmail(dot)com> wrote:
>
> 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.

yes agreed. The patch v10-0003 attempts to do the same.

> 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.
>

Do you mean the logical replication launcher builds a shared memory
structure based
on the number of 'dbs' to sync as I understood from your initial comment?

thanks
Shveta