Re: Conflict detection for update_deleted in logical replication

On Sat, May 24, 2025 at 4:46 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>
> This sounds reasonable to me. Let us see what others think.
>

I was looking into the for getting the transaction status from
publisher, what I would assume this patch should be doing is request
the publisher status first time, and if some transactions are still in
commit, then we need to wait for them to get completed. But in the
current design its possible that while we are waiting for in-commit
transactions to get committed the old running transaction might come
in commit phase and then we wait for them again, is my understanding
not correct?

Maybe this is very corner case that there are thousands of old running
transaction and everytime we request the status we find some
transactions is in commit phase and the process keep running for long
time until all the old running transaction eventually get committed.

I am thinking can't we make it more deterministic such that when we
get the status first time if we find some transactions that are in
commit phase then we should just wait for those transaction to get
committed? One idea is to get the list of xids in commit phase and
next time when we get the list we can just compare and in next status
if we don't get any xids in commit phase which were in commit phase
during previous status then we are done. But not sure is this worth
the complexity? Mabe not but shall we add some comment explaining the
case and also explaining why this corner case is not harmful?

--
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com