Re: DROP COLUMN misbehaviour with multiple inheritance - Mailing list pgsql-hackers

From Bruce Momjian
Subject Re: DROP COLUMN misbehaviour with multiple inheritance
Date
Msg-id 200210031931.g93JVZM05601@candle.pha.pa.us
Whole thread Raw
In response to Re: DROP COLUMN misbehaviour with multiple inheritance  (Alvaro Herrera <alvherre@atentus.com>)
Responses Re: DROP COLUMN misbehaviour with multiple inheritance  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
Where are we with this patch?

---------------------------------------------------------------------------

Alvaro Herrera wrote:
> On 29 Sep 2002, Hannu Krosing wrote:
> 
> > On Sun, 2002-09-29 at 19:57, Tom Lane wrote:
> > > Hannu Krosing <hannu@tm.ee> writes:
> > > > I'd propose that ADD ONLY would pull topmost attislocal up (reset it
> > > > from the (grand)child) whereas plain ADD would leave attislocal alone.
> > > 
> > > ADD ONLY?  There is no such animal as ADD ONLY, and cannot be because
> > > it implies making a parent inconsistent with its children. 
> > 
> > I meant ADD ONLY to be the exact opposite of DROP ONLY - it adds parent
> > column and removes attislocal from children. Simple ADD would _not_
> > remove attislocal from children with matching column.
> 
> Consistency requires that it be exactly the opposite.  When you ADD
> ONLY, you want only in the "local" table, so children still have a local
> definition; OTOH, when you ADD (recursively) you want all children to
> get non-local status.
> 
> Suppose
> CREATE TABLE p (f1 int);
> CREATE TABLE c (f2 int) INHERITS (p);
> c.f2.attislocal = true
> 
> Now,
> ALTER TABLE ONLY p ADD COLUMN f2 int
> should leavy c.f2.attislocal alone, while
> ALTER TABLE p ADD COLUMN f2 int
> should reset it.
> 
> This is the opposite of your proposal, and I don't think it exists in
> Tom's proposal.
> 
> I think this is also consistent with the fact that ONLY requires the
> column to exist in all children, while non-ONLY creates it where it
> doesn't exist, and merges (resetting attislocal if set -- it could be
> inherited from some other parent) where it exists.
> 
> -- 
> Alvaro Herrera (<alvherre[@]dcc.uchile.cl>)
> "Nunca se desea ardientemente lo que solo se desea por razon" (F. Alexandre)
> 
> 
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--  Bruce Momjian                        |  http://candle.pha.pa.us pgman@candle.pha.pa.us               |  (610)
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