RE: Synchronizing slots from primary to standby

On Thursday, February 8, 2024 7:07 PM shveta malik <shveta(dot)malik(at)gmail(dot)com>
>
> On Thu, Feb 8, 2024 at 4:03 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> >
> > Few comments on 0001
> > ===================
> > 7.
> > + /*
> > + * The primary_slot_name is not set yet or WALs not received yet.
> > + * Synchronization is not possible if the walreceiver is not started.
> > + */
> > + latestWalEnd = GetWalRcvLatestWalEnd();
> > + SpinLockAcquire(&WalRcv->mutex); if ((WalRcv->slotname[0] == '\0')
> > + ||
> > + XLogRecPtrIsInvalid(latestWalEnd))
> > + {
> > + SpinLockRelease(&WalRcv->mutex);
> > + return false;
> >
> > For the purpose of 0001, we should give WARNING here.

Fixed.

Here is the V82 patch set which includes the following changes:

0001
1. Fixed one miss that the size of shared memory for slot sync was not counted
in CalculateShmemSize().
2. Added a warning message if walreceiver has not started yet.
2. Fixed the above comment.

0002 - 0003
Rebased

0004
1. Added more details that user should run second query on standby after the
primary is down.
2. Mentioned that the query needs to be run on the db that includes the failover subscription.
Thanks Shveta for working on the changes.

Best Regards,
Hou zj