Re: Re: Changing the default value of an inherited column - Mailing list pgsql-hackers

From Peter Eisentraut
Subject Re: Re: Changing the default value of an inherited column
Date
Msg-id Pine.LNX.4.30.0103291851120.2091-100000@peter.localdomain
Whole thread Raw
In response to Re: Re: Changing the default value of an inherited column  ("Oliver Elphick" <olly@lfix.co.uk>)
List pgsql-hackers
Oliver Elphick writes:

> Peter Eisentraut wrote:
>   >Tom Lane writes:
>   >
>   >> It seems that in pre-7.0 Postgres, this works:
>   >>
>   >> create table one(id int default 1, descr text);
>   >> create table two(id int default 2, tag text) inherits (one);
>   >>
>   >> with the net effect that table "two" has just one "id" column with
>   >> default value 2.
>   >
>   >Although the liberty to do anything you want seems appealing at first, I
>   >would think that allowing this is not correct from an OO point of view.
>
> I don't agree; this is equivalent to redefinition of a feature (=method) in
> a descendant class, which is perfectly acceptable so long as the feature's
> signature (equivalent to column type) remains unchanged.

The SQL equivalent of redefining a method would the redefinition of a
method [sic].  But since we don't have anything close to that, feel
free...

-- 
Peter Eisentraut      peter_e@gmx.net       http://yi.org/peter-e/



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