Re: Introduce XID age and inactive timeout based replication slot invalidation

On Fri, Feb 7, 2025 at 8:00 AM Peter Smith <smithpb2250(at)gmail(dot)com> wrote:
>
> ======
> src/backend/access/transam/xlog.c
>
> 1.
> XLByteToSeg(RedoRecPtr, _logSegNo, wal_segment_size);
> KeepLogSeg(recptr, &_logSegNo);
> - if (InvalidateObsoleteReplicationSlots(RS_INVAL_WAL_REMOVED,
> + if (InvalidateObsoleteReplicationSlots(RS_INVAL_WAL_REMOVED |
> RS_INVAL_IDLE_TIMEOUT,
> _logSegNo, InvalidOid,
> InvalidTransactionId))
> {
> @@ -7792,7 +7792,7 @@ CreateRestartPoint(int flags)
> replayPtr = GetXLogReplayRecPtr(&replayTLI);
> endptr = (receivePtr < replayPtr) ? replayPtr : receivePtr;
> KeepLogSeg(endptr, &_logSegNo);
> - if (InvalidateObsoleteReplicationSlots(RS_INVAL_WAL_REMOVED,
> + if (InvalidateObsoleteReplicationSlots(RS_INVAL_WAL_REMOVED |
> RS_INVAL_IDLE_TIMEOUT,
> _logSegNo, InvalidOid,
> InvalidTransactionId))
>
> It seems fundamentally strange to me to assign multiple simultaneous
> causes like this. IMO you can't invalidate something that is invalid
> already. I gues v71 was an attempt to implement Amit's:
>

The idea is to invalidate the slot either due to WAL_REMOVED or
IDLE_TIMEOUT in one go during the checkpoint instead of taking
multiple passes over the slots during the checkpoint. Feel free to
suggest if you can think of a better way to implement it.

--
With Regards,
Amit Kapila.