Re: Introduce XID age and inactive timeout based replication slot invalidation

On Wed, Mar 6, 2024 at 4:28 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>
> IIUC, the current conflict_reason is primarily used to determine
> logical slots on standby that got invalidated due to recovery time
> conflict. On the primary, it will also show logical slots that got
> invalidated due to the corresponding WAL got removed. Is that
> understanding correct?

That's right.

> If so, we are already sort of overloading this
> column. However, now adding more invalidation reasons that won't
> happen during recovery conflict handling will change entirely the
> purpose (as per the name we use) of this variable. I think
> invalidation_reason could depict this column correctly but OTOH I
> guess it would lose its original meaning/purpose.

Hm. I get the concern. Are you okay with having inavlidation_reason
separately for both logical and physical slots? In such a case,
logical slots that got invalidated on the standby will have duplicate
info in conflict_reason and invalidation_reason, is this fine?

Another idea is to make 'conflict_reason text' as a 'conflicting
boolean' again (revert 007693f2a3), and have 'invalidation_reason
text' for both logical and physical slots. So, whenever 'conflicting'
is true, one can look at invalidation_reason for the reason for
conflict. How does this sound?

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