Re: Proposal: Conflict log history table for Logical Replication

On Tue, Dec 9, 2025 at 8:41 PM Dilip Kumar <dilipbalaut@gmail.com> wrote:
>
> >
> Here is the updated version of patch
> What has changed
> 1. Table is created using create_heap_with_catalog() instead of SPI as
> suggested by Sawada-San and Amit Kapila.
> 2. Validated the table schema after acquiring the lock before
> preparing/inserting conflict tuples for defects raised by Vignesh.
> 3. Bug fixes raised by Shweta (segfault)
> 3. Comments from Peter (except exposing namespace in \dRs+, it's still pending.
>

Thanks for the patch.
I tested all conflict-types on this version, they (basic scenarios)
seem to work well. Except only that key-RI pending issue, other issues
seem to be addressed. I will start with code-review now.

Few observations:

1)
\dRs+  shows 'Conflict log table' without namespace, this could be
confusing if the same table exists in multiple schemas.

2)
When we do below:
alter subscription sub1 SET (conflict_log_table=clt2);

the previous conflict log table is dropped. Is this behavior
intentional and discussed/concluded earlier? It’s possible that a user
may want to create a new conflict log table for future events while
still retaining the old one for analysis. If the subscription itself
is dropped, then dropping the CLT makes sense, but I’m not sure this
behavior is intended for ALTER SUBSCRIPTION.  I do understand that
once we unlink CLT from subscription, later even DROP subscription
cannot drop it, but user can always drop it when not needed.

If we plan to keep existing behavior, it should be clearly documented
in a CAUTION section, and the command should explicitly log the table
drop.

thanks
Shveta