Re: [HACKERS] Enums patch v2

Alvaro Herrera <alvherre(at)commandprompt(dot)com> writes:
> I don't, because there are always those that are knowledgeable enough to
> know how to reduce space lost to padding. So it would be nice to have
> 2-byte enums on-disk, and resolve them based on the column's typid. But
> then, I'm not familiar with the patch at all so I'm not sure if it's
> possible.

Remember that the value has to be decodable by the output routine.
So the only way we could do that would be by creating a separate output
function for each enum type. (That is, a separate pg_proc entry
... they could all point at the same C function, which would have to
check which OID it was called as and work backward to determine the enum
type.)

While this is doubtless doable, it's slow, it bloats pg_proc, and
frankly no argument has been offered that's compelling enough to
require it. The alignment issue takes enough air out of the
space-saving argument that it doesn't seem sufficient to me.

regards, tom lane