On 2021-Apr-26, Tom Lane wrote: > Stephen Frost <sfr...@snowman.net> writes: > > * Magnus Hagander (mag...@hagander.net) wrote: > >> Thatäs why I suggested the three value one. Default to a mode where > >> it's automatic, which is what the majority is going to want, but have > >> a way to explicitly turn it on. > > > This is certainly fine with me too, though it seems a bit surprising to > > me that we couldn't just figure out what the user actually wants based > > on what's installed/running for any given combination. > > I'd be on board with having pg_stat_statement's pg_init function do > something to adjust the setting, if we can figure out how to do that > in a way that's not confusing in itself. I'm not sure though that > the GUC engine offers a good way.
I think it's straightforward, if we decouple the tri-valued enum used for guc.c purposes from a separate boolean that actually enables the feature. GUC sets the boolean to "off" initially when it sees the enum as "auto", and then pg_stat_statement's _PG_init modifies it during its own startup as needed. So the user can turn the GUC off, and then pg_stat_statement does nothing and there is no performance drawback; or leave it "auto" and it'll only compute query_id if pg_stat_statement is loaded; or leave it on if they want the query_id for other purposes. -- Álvaro Herrera 39°49'30"S 73°17'W "El miedo atento y previsor es la madre de la seguridad" (E. Burke)
