On Wed, Mar 23, 2022 at 12:53 AM Julien Rouhaud <rjuju...@gmail.com> wrote: > Unless I'm missing something, the new situation is that the system is supposed > to prevent access to MaxBackends during s_p_l_pg_init, for reasons I totally > agree with, but without doing anything for extensions that actually need to > access it at that time. So what are extensions supposed to do now if they do > need the information during their _PG_init() / RequestAddinShmemSpace()?
Well, the conclusion upthread was that extensions might change the values of those GUCs from _PG_init(). If that's a real thing, then what you're asking for here is impossible, because the final value is indeterminate until all such extensions have finished twiddling those the GUCs. On the other hand, it's definitely intended that extensions should RequestAddinShmemSpace() from _PG_init(), and wanting to size that memory based on MaxBackends is totally reasonable. Do we need to add another function, alongside _PG_init(), that gets called after MaxBackends is determined and before it's too late to RequestAddinShmemSpace()? -- Robert Haas EDB: http://www.enterprisedb.com
