On Mon, Dec 1, 2025 at 12:54 AM shveta malik <[email protected]> wrote: > > On Mon, Dec 1, 2025 at 11:40 AM Masahiko Sawada <[email protected]> wrote: > > > > > > > 11) > > > my ($result, $stdout, $stderr) = $standby4->psql('postgres', > > > qq[select pg_logical_slot_get_changes('standby4_slot', null, null)]); > > > like( > > > $stderr, > > > qr/ERROR: logical decoding on standby requires "effective_wal_level" > > > >= "logical" on the primary/, > > > "cannot use logical decoding on standby as it is disabled on primary"); > > > > > > Since the slot is invalidated, shouldn't the better error message be > > > what we usually get: > > > ERROR: can no longer access replication slot "slot" > > > DETAIL: This replication slot has been invalidated due to "..". > > > > > > IMO, the 'invalidated' message is better because even if we enable > > > logical-decoding on primary, it is of no use for this slot. > > > > > > But I also see the difficulty in achieving this, as the > > > primary-related error message is by CheckLogicalDecodingRequirements() > > > which happens earlier than > > > ReplicationSlotAcquire(). So if there is no better way, we can leave it > > > as is. > > > > We can achieve it by creating another valid logical slot, but I > > believe that we already have tests to check if we cannot use an > > invalidated slot. What we want to test here is if logical decoding is > > disabled by invalidating the last logical slot. So I think the test > > works as expected. > > > > Sorry for the confusion. My earlier comment wasn’t about the test > mechanics or correctness. I meant that when a slot is invalidated and > someone attempts to use it, the message should reflect that (can no > longer access replication slot "slot"). Currently, the message > suggests enabling logical decoding on the primary, even though that > won’t make an invalidated slot usable. IMO, it would be clearer to > report that the slot is invalidated instead of directing the user to > enable decoding on primary.
Hmm, I'm not sure there is a big difference there. If we show the message first that indicates that the slot is invalidated, users would drop the slot and try to create a new logical slot, but they would get the error 'logical decoding on standbys requires "effective_wal_level" >= "logical" on the primary'. With the current implementation, they would enable logical decoding on the primary first, realize that the slot on the standby is already invalidated, and then create a new logical slot. Regards, -- Masahiko Sawada Amazon Web Services: https://aws.amazon.com
