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.
It'll simplify the SQL to pass it a pg_class.relnamespace value, since that's what's stored in pg_class.
select ...
from pg_class cl INNER JOIN ...
where not is_system_schema(cl.relnamespace)
and ...;
Might it be slightly slower? Sure... but pg_class and pg_namespace aren't giant tables, and the queries won't run thousands of times per day. Thus, in this case, a little less efficiency for much cleaner code is an acceptable trade-off TO ME.
Heck, given how often "pg_class cl INNER JOIN pg_namespace nsp ON cl.relnamespace = nsp.oid" appears in my (and so much other code around the Internet), I should probably create a view that joins the two tables, and adds an is_system_schema column.
That would really simplify my code...
-- Death to <Redacted>, and butter sauce.
Don't boil me, I'm still alive.
