Re: Request for comment on setting binary format output per session

Jeff Davis <pgsql@j-davis.com> writes:
> On Sat, 2023-03-04 at 18:04 -0500, Dave Cramer wrote:
>> Most of the clients know how to decode the builtin types. I'm not
>> sure there is a use case for binary encode types that the clients
>> don't have a priori knowledge of.

> The client could, in theory, have a priori knowledge of a non-builtin
> type.

I don't see what's "in theory" about that.  There seems plenty of
use for binary I/O of, say, PostGIS types.  Even for built-in types,
do we really want to encourage people to hard-wire their OIDs into
applications?

I don't see a big problem with driving this off a GUC, but I think
it should be a list of type names not OIDs.  We already have plenty
of precedent for dealing with that sort of thing; see search_path
for the canonical example.  IIRC, there's similar caching logic
for temp_tablespaces.