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
