Re: has_column_privilege behavior (was Re: Assert failed in snprintf.c)

Stephen Frost <sfrost@snowman.net> writes:
> * Tom Lane (tgl@sss.pgh.pa.us) wrote:
>> The general plan in the has_foo_privilege functions is to throw errors for
>> failing name-based lookups, but return null for failing numerically-based
>> lookups (object OID or column number).  I'm inclined to think we should
>> stick to that.  In the case at hand, we'd be supporting queries that
>> iterate over pg_attribute, but they'd have to pass attnum not attname
>> to avoid snapshot-skew failures.  That's a bit annoying, but not throwing
>> error for a typo'ed name is annoying to a different and probably larger
>> set of users.

> ... and what's going to happen when they pass in a dropped column,
> either via number or name?

Well, it'll have to fail for the name case, but not for the attnum case.

> I don't have an issue with throwing a failure for name-based lookups but
> returning null for failing numerically-based lookups, but I don't really
> want us throwing errors on dropped columns.  I would think we'd return
> null in that case.

You can't have it both ways.  Either you throw an error if the name's
not there, or you don't.

> In particular, I can see this function being used in
> a where clause across pg_attribute.

As said above, it can work as long as you use attnum not attname.
I don't think this is really so different from iterating across
pg_class (or any other catalog) and passing relname instead of OID.

            regards, tom lane