On Sun, 15 Dec 2024 at 14:20, Tom Lane <t...@sss.pgh.pa.us> wrote: > Isaac Morland <isaac.morl...@gmail.com> writes: > > On Sun, 15 Dec 2024 at 12:29, Tom Lane <t...@sss.pgh.pa.us> wrote: > >> What I'd suggest as an improvement that could be implemented > >> immediately is to wrap the checks in a user-defined function > >> like "is_system_schema(nspname name)". > > > Would it make sense to make the parameter be of type regnamespace? > > Meh ... you could, but what the function really needs is the name. > Getting from regnamespace (which is an OID) to the name would incur > an extra syscache lookup. Admittedly, if it removes the need for > the calling query to join to pg_namespace at all, you'd probably > come out about even --- the net effect would be about like a > hashjoin to pg_namespace, I think, since the syscache would act > like the inner hashtable of a hashjoin.
Thanks for the critique. It occurs to me that this function is perhaps just as much about “is this name a system-reserved name?” as “is this schema a system schema?”. So putting in a name that doesn’t actually exist in the database should be perfectly valid, which of course only works if it takes a string. Generally speaking I am a big fan of the reg* data types but in this specific case I think it’s not a clear win. I might still suggest providing both versions using function overloading.
