On Fri, Apr 25, 2025 at 4:06 PM shveta malik <shveta.ma...@gmail.com> wrote: > > 2) > in wait_for_local_flush(), we have > should_stop_conflict_info_retention() before 'AllTablesyncsReady' > check. Should we give a discount for table-sync time and avoid doing > stop-conflict-retention when table-sync is going on? This is because > table-sync is one time operation (or done only on > subscription-refresh), so we shall not count time spent in table-sync > for 'max_conflict_retention_duration'. We can reset our timer if > table-sync is observed to be going on. Thoughts? >
Sounds reasonable to me. > > 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. > Good point. I think we should set 'candidate_xid_time' along with candidate_xid (just after setting candidate_xid). > 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. > Right, ideally, the 'xid_advance_interval' should be set to a value less than 'max_conflict_retention_duration' when no new_xid is found. BTW, another related point is that when we decide to stop retaining dead tuples (via should_stop_conflict_info_retention), should we also consider the case that the apply worker didn't even try to get the publisher status because previously it decided that oldest_nonremovable_xid cannot be advanced due to its OldestActiveTransactionId? -- With Regards, Amit Kapila.
