Message-ID: <40AA5C56.2030105@archonet.com>
Date: Tue, 18 May 2004 19:56:22 +0100
From: Richard Huxton <dev@archonet.com>
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To: Ricardo Maia <maia@univap.br>, pgsql-sql@postgresql.org
Subject: Using "Without OIDs"
References: <20040517163736.23605.qmail@web20311.mail.yahoo.com>	
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	<1084904813.52367.44.camel@jerusalem.univap.br>
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Ricardo Maia wrote:
> Hi,
> 
> I'm from Brazil, and i have a question.

Hi Ricardo, happy to help, but three points:
  1. Always make sure you use "reply to all" on the PostgreSQL lists
  2. For a new question, send a new message to pgsql-sql@postgresql.org, 
since most direct email to this address goes into my spam bin.
  3. You caught the subject-line change yourself in your next posting.

> Exists some problem if i not uses the option "without oids"?
> I read the manual, but I don't understand what I earn if i use it.

The OIDs are used by PostgreSQL's system tables. So, you can do 
something like
   SELECT oid,relname,reltype FROM pg_class;
This will give you the number PG uses to refer to tables (etc.), the 
name you use and the type of thing it is. This type is also an OID.

These OIDs were never really meant to be for user-tables, but some 
people used them as a default primary-key. This was a bad idea, but 
since the column was always there you couldn't stop them.

The developers couldn't just turn OIDs off for user tables without 
breaking some applications, so they added an option to say you didn't 
want them. If you specify you don't want OIDs that table will use 4 
bytes less for every row, and so be a bit faster.

I believe in the next version, the default setting will be not to have 
OIDs and you will have to specify "WITH OIDS" if you do want them.

HTH
-- 
   Richard Huxton
   Archonet Ltd