Isaac Morland <isaac.morland@gmail.com> writes: > On Sun, 15 Dec 2024 at 12:29, Tom Lane <tgl@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.
