Re: error-free disabling of individual child partition - Mailing list pgsql-hackers

From Alvaro Herrera
Subject Re: error-free disabling of individual child partition
Date
Msg-id 20060524151603.GG3159@surnet.cl
Whole thread Raw
In response to Re: error-free disabling of individual child partition  (Hannu Krosing <hannu@skype.net>)
Responses Re: error-free disabling of individual child partition
List pgsql-hackers
Hannu Krosing wrote:
> Ühel kenal päeval, K, 2006-05-24 kell 09:40, kirjutas Tom Lane:
> > Simon Riggs <simon@2ndquadrant.com> writes:
> > > On Wed, 2006-05-24 at 11:17 +0300, Hannu Krosing wrote:
> > >> Why "never set back again" ? I'd guess that it should be set back to
> > >> true when it is not an inherited column anymore, that is when its
> > >> attinhcount reaches zero.
> > 
> > > Because you have no record of whether it was created locally or
> > > inherited when originally created. And: do you care? Why?
> > 
> > The invariant is supposed to be that every attribute has attislocal
> > true or attinhcount > 0 (or both). 
> 
> In what case does it have both ?

create table parent (foo int);
create table child (foo int) inherits (parent);

In the child, the column is local but it's also inherited from parent.
So if you drop the column from the parent, it should be kept in the
child.

> >  Otherwise it has no justification
> > to exist.  I see in the regression database that someone has broken
> > this invariant; it looks like LIKE inheritance is misimplemented.
> 
> I don't think that LIKE inheritance is inheritance at all, rather it is
> a create-time macro.

In that case the columns should be marked attislocal.

-- 
Alvaro Herrera                                http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.


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