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

On Wed, Mar 13, 2024 at 9:21 AM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>
> > So, how about we turn conflict_reason to only report the reasons that
> > actually cause conflict with recovery for logical slots, something
> > like below, and then have invalidation_cause as a generic column for
> > all sorts of invalidation reasons for both logical and physical slots?
>
> If our above understanding is correct then coflict_reason will be a
> subset of invalidation_reason. If so, whatever way we arrange this
> information, there will be some sort of duplicity unless we just have
> one column 'invalidation_reason' and update the docs to interpret it
> correctly for conflicts.

Yes, there will be some sort of duplicity if we emit conflict_reason
as a text field. However, I still think the better way is to turn
conflict_reason text to conflict boolean and set it to true only on
rows_removed and wal_level_insufficient invalidations. When conflict
boolean is true, one (including all the tests that we've added
recently) can look for invalidation_reason text field for the reason.
This sounds reasonable to me as opposed to we just mentioning in the
docs that "if invalidation_reason is rows_removed or
wal_level_insufficient it's the reason for conflict with recovery".

Thoughts?

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