Tino Wildenhain wrote:
> Google or your favourite search engine helps :-)
>
> http://www.postgresql.org/files/documentation/books/aw_pgsql/node71.html
>
> is among the first results.
Unfortunately those docs are quite out of date. This page is better:
http://developer.postgresql.org/docs/postgres/datatype-oid.html
(This describes the behavior that will be the default in 8.1)
Specifically:
Object identifiers (OIDs) are used internally by PostgreSQL as primary
keys for various system tables.... The oid type is currently implemented
as an unsigned four-byte integer. Therefore, it is not large enough to
provide database-wide uniqueness in large databases, or even in large
individual tables. So, using a user-created table's OID column as a
primary key is discouraged. OIDs are best used only for references to
system tables.
-Neil