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Re: unique ID across all columns
- From: Alvaro Herrera <alvherre(at)commandprompt(dot)com>
- To: Felix Kater <fkater(at)googlemail(dot)com>
- Cc: pgsql-general(at)postgresql(dot)org
- Subject: Re: unique ID across all columns
- Date: Tue, 17 Apr 2007 10:17:39 -0400
- Message-id: <20070417141739(dot)GB7436(at)alvh(dot)no-ip(dot)org>
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.
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