Re: Conflict detection for update_deleted in logical replication

On Fri, Apr 25, 2025 at 4:05 PM shveta malik <shveta(dot)malik(at)gmail(dot)com> wrote:
>
> >
> > Here is V30 patch set includes the following changes:
> >
>
> Thank You for the patch, please find few concerns:
>

Please find few more concerns:

3)
In get_candidate_xid(), we first set candidate_xid_time and later
candidate_xid. And between these 2 there are chances that we return
without updating candidate_xid. See 'Return if the
oldest_nonremovable_xid cannot be advanced ' comment. That will leave
'candidate_xid_time' set to new value while 'candidate_xid' is not
yet set.

4)
Do you think there should be some relation between
'xid_advance_interval' and 'max_conflict_retention_duration'? Should
max of 'xid_advance_interval' be limited by
'max_conflict_retention_duration'. Currently say
xid_advance_interval' is set to max 3 mins, what if
'max_conflict_retention_duration' is set to 2 mins? In that case we
will not even check for new xids before 3 mins are over, while
'max_conflict_retention_duration' sets a limit of 2 mins for dead
tuples retention.

thanks
Shveta