On Thu, Dec 21, 2023 at 11:18 AM Michael Paquier <mich...@paquier.xyz> wrote: > > On Thu, Dec 21, 2023 at 09:37:39AM +0530, Amit Kapila wrote: > > It depends on how one uses the function. For example, if one finds > > there is a conflict via pg_get_replication_slots() and wants to check > > the reason for the same via this new function then it would give the > > correct answer. > > My point is that we may not get the "correct" answer at all :/ > > What guarantee do you have that between the scan of > pg_get_replication_slots() to get the value of "conflicting" and the > call of pg_get_slot_invalidation_cause() the slot state will still be > the same? >
Yeah, if one uses them independently then there is no such guarantee. > A lot could happen between both function calls while the > repslot LWLock is not hold. > > > Now, if we think it is okay to have two columns > > 'conflicting' and 'conflict_reason/conflict_cause' to be returned by > > pg_get_replication_slots() then that should serve the purpose as well > > but one can argue that 'conflicting' is deducible from > > 'conflict_reason'. > > Yeah, you could keep the reason text as NULL when there is no > conflict, replacing the boolean by the text in the function, and keep > the view definition compatible with v16 while adding an extra column. > But as mentioned we also want the enum value to be exposed in some way so that it can be used by the sync slot feature [1] as well, otherwise, we may need some mappings to convert the text back to an enum. I guess if we want to expose via view, then we can return an enum value by pg_get_replication_slots() and the view can replace it with text based on the value. [1] - https://www.postgresql.org/message-id/OS0PR01MB5716DAF72265388A2AD424119495A%40OS0PR01MB5716.jpnprd01.prod.outlook.com -- With Regards, Amit Kapila.
