On Tue, Apr 12, 2022 at 03:30:23PM -0400, Robert Haas wrote: > On Tue, Apr 12, 2022 at 3:22 PM Tom Lane <t...@sss.pgh.pa.us> wrote: >> Yeah. It's a very long way from "changing shared memory sizes here >> doesn't work" to "no extension is allowed to change any GUC at load >> time". A counterexample is that it's not clear why an extension >> shouldn't be allowed to define a GUC using DefineCustomXXXVariable >> and then immediately set it to some other value. I think trying to >> forbid that across-the-board is going to mostly result in breaking >> a lot of cases that are perfectly safe. > > Hmm, that's an interesting case which I hadn't considered. It seems > like sort of a lame thing to do, because why wouldn't you just create > the GUC with the right initial value instead of modifying it after the > fact? But maybe there's some use case in which it makes sense to do it > that way. A read-only GUC that advertises some calculated value, > perhaps?
I think it'd be reasonable to allow changing custom GUCs in _PG_init(). Those aren't going to impact things like MaxBackends. -- Nathan Bossart Amazon Web Services: https://aws.amazon.com
