Hi,
On 11/13/23 2:57 PM, Zhijie Hou (Fujitsu) wrote:
On Friday, November 10, 2023 4:16 PM Drouvot, Bertrand
<bertranddrouvot...@gmail.com> wrote:
Yeah good point, agree to just error out in all the case then (if we discard the
sync_ reserved wording proposal, which seems to be the case as probably not
worth the extra work).
Thanks for the discussion!
Here is the V33 patch set which includes the following changes:
Thanks for working on it!
1) Drop slots with state 'i' in promotion flow after we shut down WalReceiver.
@@ -3557,10 +3558,15 @@ WaitForWALToBecomeAvailable(XLogRecPtr RecPtr, bool
randAccess,
* this only after failure, so when you promote, we still
* finish replaying as much as we can from archive and
* pg_wal before failover.
+ *
+ * Drop the slots for which sync is initiated but not yet
+ * completed i.e. they are still waiting for the primary
+ * server to catch up.
*/
if (StandbyMode && CheckForStandbyTrigger())
{
XLogShutdownWalRcv();
+ slotsync_drop_initiated_slots();
return XLREAD_FAIL;
}
I had a closer look and it seems this is not located at the right place.
Indeed, it's added here:
switch (currentSource)
{
case XLOG_FROM_ARCHIVE:
case XLOG_FROM_PG_WAL:
While in our case we are in
case XLOG_FROM_STREAM:
So I think we should move slotsync_drop_initiated_slots() in the
XLOG_FROM_STREAM case. Maybe before shutting down the sync slot worker?
(the TODO item number 2 you mentioned up-thread)
BTW in order to prevent any corner case, would'nt also be better to
replace:
+ /*
+ * Do not allow consumption of a "synchronized" slot until the standby
+ * gets promoted.
+ */
+ if (RecoveryInProgress() && (slot->data.sync_state != SYNCSLOT_STATE_NONE))
with something like:
if ((RecoveryInProgress() && (slot->data.sync_state != SYNCSLOT_STATE_NONE)) ||
slot->data.sync_state == SYNCSLOT_STATE_INITIATED)
to ensure slots in 'i' case can never be used?
Regards,
--
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com
