Re: Altering a table - positioning new columns

From: Manfred Koizar <mkoi-pg(at)aon(dot)at>
To: "Chris Boget" <chris(at)wild(dot)net>
Cc: "PGSql General" <pgsql-general(at)postgresql(dot)org>
Subject: Re: Altering a table - positioning new columns
Date: 2003-01-20 16:05:53
Message-ID: jt6o2vo2hp54tvuf8eckmfhj1sa93sc9co@4ax.com
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On Mon, 20 Jan 2003 09:28:50 -0600, "Chris Boget" <chris(at)wild(dot)net>
wrote:
>I'm curious how difficult this would be to implement...

The current implementation has the benefit that when you add a column
existing tuples don't have to be touched. Each tuple header stores
the number of attributes (natts) at the time of its creation. If you
query for an attribute with a higher number, you get NULL. I don't
think this can be changed easily without breaking lots of things.

Mid-2002 there has been rudimentary discussion about metadata
versioning, but it didn't get beyond its brainstorming phase ...

Servus
Manfred

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