Re: Enum proposal / design

Tom Dunstan <pgsql(at)tomd(dot)cc> writes:
> Andrew Dunstan wrote:
>> I'm inclined to say let's keep it simple and stay with a fixed 4-byte
>> global size.

> Fair enough. I'm ok with 4 bytes; 8 seemed a bit gratuitous.

If you're gonna fix it at 4 bytes, then I strongly suggest that the
value identifiers actually be OIDs assigned through the standard
OID-generating mechanism, and that the pg_enum table have the structure

standard system OID column unique enum-value identifier
enumtypid OID of enum type it belongs to
enumname name of enum value

unique indexes on:
oid
(enumtypid, enumname)

The advantage of doing this is that you can use the existing, well
debugged, normally-quite-fast mechanisms for generating new unique value
identifiers. Rather than consing up your own slow full-table-scan
mechanism as envisioned in the original proposal.

regards, tom lane