Re: Fixes for missing schema qualifications

On Sat, Mar 10, 2018 at 08:36:34AM +0000, Noah Misch wrote:
> This qualifies some functions, but it leaves plenty of unqualified operators.

Yeah, I know that, and i don't have a perfect reply to offer to you.
There are a couple of methods that we could use to tackle that:
1) For functions, enforce search_path with a SET search_path =
'pg_catalog' command.  However this has a performance impact.
2) Enforce operators qualification with operator(pg_catalog.foo).  This
has no impact on performance, but repeating that all over the place is
rather ugly, particularly for psql's describe.c and tab-completion.c.
3) Tweak dynamically search_path before running a query:
- Save the existing search_path value by issuing SHOW search_path.
- Use ALWAYS_SECURE_SEARCH_PATH_SQL to enforce the path.
- Set back search_path based on the previous value.
This logic can happen in a dedicated wrapper, but this impacts
performance as it requires extra round trips to the server.

For information_schema.sql, we are talking about tweaking 12 functions.
So I think that we could live with 2). 

To simplify user's life, we
could also recommend just to users to issue a ALTER FUNCTION SET
search_path to fix the problem for all functions, that's easier to
digest.

For the rest, which basically concerns psql, I have been thinking that
actually using 2) would be the most painful approach, still something
which does not impact the user experience, while 3) is easier to
back-patch by minimizing the code footprint and avoids also any kind of
future problems.