On Fri, Nov 7, 2025 at 11:10 AM Heikki Linnakangas <[email protected]> wrote: > > On 06/11/2025 17:13, Arseniy Mukhin wrote: > > Let's say we have the queue: > > > > (tail ... pos1 ... bad_entry_pos ... head) > > > > bad_entry_pos - position of the entry where TransactionIdDidCommit fails. > > > > We have the listener L1 with pos = pos1. It means every new listener > > should process the queue from pos1 (as it's max(listener's pos)) up to > > the queue head and when they try to do it, they will fail on > > 'bad_entry'. > > Gotcha. > > >> Another small change we could make is to check for listenChannels == NIL > >> before calling TransactionIdDidCommit. > > > > There is a comment that describes why we need this initial reading in > > Exec_ListenPreCommit: > > > > /* > > * This is our first LISTEN, so establish our pointer. > > * > > * We set our pointer to the global tail pointer and then move it > > forward > > * over already-committed notifications. This ensures we cannot miss > > any > > * not-yet-committed notifications. We might get a few more but that > > * doesn't hurt. > > > > It seems that with such a check we will skip not-yet-committed > > notifications and always get to the HEAD. If we decide that it's ok, > > maybe we can just set 'pos' of every new listener to the HEAD without > > reading? > > Right, I didn't mean skipping asyncQueueReadAllNotifications() > altogether. Just the TransactionIdDidCommit() calls in it, when > listenChannels == NIL, see attached patch. The idea is that when > 'listenChannels == NIL', we're not going send the notification to the > frontend regardless of what TransactionIdDidCommit says. If we don't > call TransactionIdDidCommit, we won't fail on bad entries. >
Ahh, now I see, thank you. WFM. Best regards, Arseniy Mukhin
