Hi, On 2020-06-08 13:27:50 -0400, Tom Lane wrote: > If we can allow wal_level to be changed on the fly, I agree that would > help reduce the pressure to make the default setting more expensive. > I don't recall why it's PGC_POSTMASTER right now, but I suppose there > was a reason for that ...
There's reasons, but IIRC they're all solvable with reasonable effort. I think most of it boils down to only being able to rely on the new wal_level after a while. For minimal->recovery we basically need a checkpoint started after the change in configuration, and for recovery->logical we need to wait until all sessions have a) read the new config setting b) finished the transaction that used the old setting. Greetings, Andres Freund
