On 2018-10-29 16:02:18 -0300, Alvaro Herrera wrote: > On 2018-Oct-29, Joshua D. Drake wrote: > > > -Hackers, > > > > > > Working on 9.6 today (unsure if fixed in newer versions). Had an issue where > > the wal was 280G despite max_wal_size being 8G. Found out there were stale > > replication slots from a recent base backup. I went to drop the replication > > slots and found that since the wal_level was set to minimal vs replica or > > higher, I couldn't drop the replication slot. Clearly that makes sense for > > creating a replication slot but it seems like an artificial limitation for > > dropping them. > > This sounds closely related to > https://www.postgresql.org/message-id/20180508143725.mn3ivlyvgpul6ovr%40alvherre.pgsql > (commit a1f680d962ff) wherein we made it possible to drop a slot in > single-user mode. > > Seems worth fixing. Send a patch?
I don't think this quite is the problem. ISTM the issue is rather that StartupReplicationSlots() *needs* to check whether wal_level > minimal, and doesn't. So you can create a slot, shutdown, change wal_level, startup. A slot exists but won't work correctly. Greetings, Andres Freund
