On 11/2/21, 9:46 AM, "Robert Haas" <robertmh...@gmail.com> wrote: > On Tue, Nov 2, 2021 at 12:39 PM Bossart, Nathan <bossa...@amazon.com> wrote:> >> On 11/2/21, 9:17 AM, "Robert Haas" <robertmh...@gmail.com> wrote: >> You could still introduce GUCs in _PG_init(), but they couldn't be >> defined as PGC_POSTMASTER. > > It seems like PGC_POSTMASTER isn't very desirable anyway. Wouldn't you > want PGC_SIGHUP? I mean I'm not saying there couldn't be a case where > that wouldn't work, because you could need a big chunk of shared > memory allocated at startup time or something. But in that's probably > not typical, and if it does happen well then that particular archive > module has to be preloaded. If you know that you have several archive > modules that you want to use, you can still preload them all if for > this or any other reason you want to do that. But in a lot of cases > it's not going to be necessary. > > In other words, if we use hooks, then you're guaranteed to need a > server restart to change anything. If we use something like what you > have now, there can be corner cases where you need that or benefits of > preloading, but it's not a hard requirement, and in many cases you can > get by without it. That seems strictly better to me ... but maybe I'm > still confused. > >> Also, you could still use >> RegisterDynamicBackgroundWorker() to register a background worker, but >> you couldn't use RegisterBackgroundWorker(). These might be >> acceptable restrictions if swapping archive libraries on the fly seems >> more important, but I wanted to bring that front and center to make >> sure everyone understands the tradeoffs. > > RegisterDynamicBackgroundWorker() seems way better, though. It's hard > for me to understand why this would be a problem for anybody. And > again, if somebody does have that need, they can always fall back to > saying that their particular module should be preloaded if you want to > use it.
I agree. I'll make sure the archive library can be changed via SIGHUP in the next revision. Nathan
