Re: unique ID across all columns

Felix Kater wrote:
> Hi,
> 
> I need a unique ID across all columns I create. Is it o.k. to
> achive this by combining pg_attribute.attnum of a column together with
> the OID of the table the column is in?
> 
> While the table's OID should be unique according to the manual, I have
> found no hints about the uniqueness of attnum -- I removed and added
> some columns and it seems that already used values are not used again.

Yes, the table OID is unique, and pg_attribute.attnum is unique as well.
They are not reused, not even when columns are dropped.

-- 
Alvaro Herrera                                http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.