On Sep 8, 2009, at 9:10 AM, Andrew Dunstan wrote:
The protocol doesn't know anything about arrays or composites, AFAIK. If it passes the type oid, it will be the oid of the array or composite type, but the receiver has no way in the protocol of knowing that the type is such an animal. Of course, it is possible to look that up in the catalog (see pg_type columns typtype, typelem and typarray). But, as I pointed out above, none of that helps you determine the info for a type that is user-defined in C.
This explains why the values are hard-coded: we can just identify the OIDs. And since hstore and citext are contrib modules, their OIDs are not known ahead of time (PostgreSQL does not hard-code them), so one would *have* to look them up. :-(
At the very least, we need to find a way to let users tell DBD::Pg how to handle certain types. DBD::Pg could then look up the appropriate OIDs when it first connects and then store them.
Thoughts? Best, David
