[ALUG] Re: PostgrSQL row ID column

On 2004-11-11 19:49:53 +0000 Chris Green chris@areti.co.uk wrote:

PostgreSQL every row has associated with it a unique indeitifier
called the oid, which can be retrieved along with the row data; 

[...]

Ahhh! I remember this now! I just dug it out of the PostgreSQL manual, which you can find online at http://www.postgresql.org/docs/7.4/static/datatype-oid.html and it explains why using them is discouraged:

Also, an OID system column is added to user-created tables (unless WITHOUT OIDS is specified at table creation time). [...]

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. [...]

Thanks for the reminder that they're there, though!