Thread

Re: Proposal: Conflict log history table for Logical Replication

Dilip Kumar <dilipbalaut@gmail.com> — 2025-12-12T04:11:58Z

On Fri, Dec 12, 2025 at 9:19 AM shveta malik <shveta.malik@gmail.com> wrote:
>
> On Thu, Dec 11, 2025 at 7:49 PM Dilip Kumar <dilipbalaut@gmail.com> wrote:
> >
> > We do not need to make the CLT dependent on the subscription because
> > the table can be dropped when the subscription is dropped anyway and
> > we are already doing it as part of drop subscription as well as alter
> > subscription when CLT is set to NONE or a different table. Therefore,
> > extending the functionality of shared dependency is unnecessary for
> > this purpose.
> >
> > Thoughts?
>
> I believe the recommendation to create a dependency was meant to
> prevent the table from being accidentally dropped during a DROP SCHEMA
> or DROP TABLE operation. That risk still remains, regardless of the
> fact that dropping or altering a subscription will result in the table
> removal. I will give this more thought and let you know if anything
> comes to mind.

I mean we can register the dependency of subscriber on table and that
will prevent dropping the tables via DROP TABLE/DROP SCHEMA, but what
I do not like is the internal error[1] in doDeletion() when someone
will try to DROP TABLE CLT CASCADE;

I suggest an alternative approach for handling this: implement a check
within the ALTER/DROP table commands. If the table is a CLT (using
IsConflictLogTable() to verify), these operations should be
disallowed. This would enhance the robustness of CLT handling by
entirely preventing external drop/alter actions. What are your
thoughts on this solution? And let's also see what Amit and Sawada-san
think about this solution.

[1]
doDeletion()
{
....
/*
* These global object types are not supported here.
*/
case AuthIdRelationId:
case DatabaseRelationId:
case TableSpaceRelationId:
case SubscriptionRelationId:
case ParameterAclRelationId:
elog(ERROR, "global objects cannot be deleted by doDeletion");
break;
}

-- 
Regards,
Dilip Kumar
Google