Re: Minimal logical decoding on standbys

On Tue, Apr 4, 2023 at 3:17 AM Drouvot, Bertrand
<bertranddrouvot(dot)pg(at)gmail(dot)com> wrote:
>
> Hi,
>
> On 4/3/23 8:10 AM, Drouvot, Bertrand wrote:
> > Hi,
> >
> > On 4/3/23 7:35 AM, Amit Kapila wrote:
> >> On Mon, Apr 3, 2023 at 4:26 AM Jeff Davis <pgsql(at)j-davis(dot)com> wrote:
> >>
> >> Agreed, even Bertrand and myself discussed the same approach few
> >> emails above. BTW, if we have this selective logic to wake
> >> physical/logical walsenders and for standby's, we only wake logical
> >> walsenders at the time of ApplyWalRecord() then do we need the new
> >> conditional variable enhancement being discussed, and if so, why?
> >>
> >
> > Thank you both for this new idea and discussion. In that case I don't think
> > we need the new CV API and the use of a CV anymore. As just said up-thread I'll submit
> > a new proposal with this new approach.
> >
>
> Please find enclosed V57 implementing the new approach in 0004.

Regarding 0004 patch:

@@ -2626,6 +2626,12 @@ InitWalSenderSlot(void)
walsnd->sync_standby_priority = 0;
walsnd->latch = &MyProc->procLatch;
walsnd->replyTime = 0;
+
+ if (MyDatabaseId == InvalidOid)
+ walsnd->kind = REPLICATION_KIND_PHYSICAL;
+ else
+ walsnd->kind = REPLICATION_KIND_LOGICAL;
+

I think we might want to set the replication kind when processing the
START_REPLICATION command. The walsender using a logical replication
slot is not necessarily streaming (e.g. when COPYing table data).

Regards,

--
Masahiko Sawada
Amazon Web Services: https://aws.amazon.com