Tyler Brock <tyler.brock@gmail.com> writes:
> I am writing a program that behaves like a Postgres backend and can see
> that if I select oid from pg_type that the type old’s could be returned in
> the Row Description message for the field’s data type and that seems to
> work.
> However, I didn’t read anywhere that these are guaranteed to be
> constant/stable so I’d like to know if this is the case. For example: is
> the old for pg_type bool = 16 on every instance of Postgres?
Hand-assigned OIDs (those below 10000) are stable in released versions.
Those above 10K might vary across installations or PG versions. You
might find it interesting to read
https://www.postgresql.org/docs/current/system-catalog-initial-data.html#SYSTEM-CATALOG-OID-ASSIGNMENT
> Also does there exist any documentation decoding what the pg_type fields
> all mean?
https://www.postgresql.org/docs/current/catalog-pg-type.html
regards, tom lane
