Re: Synchronizing slots from primary to standby

On Mon, Apr 1, 2024 at 5:05 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>
> > 2 ===
> >
> > + {
> > + if (SnapBuildSnapshotExists(remote_slot->restart_lsn))
> > + {
> >
> > That could call SnapBuildSnapshotExists() multiple times for the same
> > "restart_lsn" (for example in case of multiple remote slots to sync).
> >
> > What if the sync worker records the last lsn it asks for serialization (and
> > serialized ? Then we could check that value first before deciding to call (or not)
> > SnapBuildSnapshotExists() on it?
> >
> > It's not ideal because it would record "only the last one" but that would be
> > simple enough for now (currently there is only one sync worker so that scenario
> > is likely to happen).
> >
>
> Yeah, we could do that but I am not sure how much it can help. I guess
> we could do some tests to see if it helps.

I had a look at test-results conducted by Nisha, I did not find any
repetitive restart_lsn from primary being synced to standby for that
particular test of 100 slots. Unless we have some concrete test in
mind (having repetitive restart_lsn), I do not think that by using the
given tests, we can establish the benefit of suggested optimization.
Attached the log files of all slots test for reference,

thanks
Shveta