Subject: Re: Inherited tables and new fields
From: Oliver Elphick <olly@lfix.co.uk>
Reply-To: olly@lfix.co.uk
To: Jeff Boes <jboes@qtm.net>
Cc: pgsql-sql@postgresql.org
In-Reply-To: <D5aLc.46510$5Y.46338@cyclops.nntpserver.com>
References: <D5aLc.46510$5Y.46338@cyclops.nntpserver.com>
Content-Type: text/plain
Organization: LFIX Limited
Message-Id: <1090393887.25749.164.camel@linda>
Mime-Version: 1.0
Date: Wed, 21 Jul 2004 08:11:27 +0100
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On Tue, 2004-07-20 at 15:36, Jeff Boes wrote:
...
> Of course, had we used table inheritance, we'd do something like ...
> 
>    select * from draft_template ...
> 
> but it wouldn't do exactly what we are doing now: that is,
> fn_all_drafts() returns not only the contents of every row in the tables
> draft_XXXXX, but also an extra column indicating which table that row
> came from.

You can do that with an inheritance hierarchy like this:

    select tableoid::regclass as tablename, * from my_table;

>    create table all_drafts (editor_id integer) inherits draft_template;
> 
> What frustrates me from time to time is that if "draft_template" is
> altered to add a new column, then the function breaks because the new
> column appears in "all_drafts" as *following* editor_id. The column
> order messes up the code in the function, because it's expecting
> all_drafts to look like draft_template, with editor_id added at the end.
> 
> Is this a mis-feature?

New columns get added at the end of each table; that is standard.

-- 
Oliver Elphick                                          olly@lfix.co.uk
Isle of Wight                              http://www.lfix.co.uk/oliver
GPG: 1024D/A54310EA  92C8 39E7 280E 3631 3F0E  1EC0 5664 7A2F A543 10EA
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