From: | "Hiroshi Inoue" <Inoue(at)tpf(dot)co(dot)jp> |
---|---|
To: | "Hannu Krosing" <hannu(at)tm(dot)ee> |
Cc: | "Don Baccus" <dhogaza(at)pacifier(dot)com>, "PostgreSQL Development" <pgsql-hackers(at)postgreSQL(dot)org>, "Peter Eisentraut" <peter_e(at)gmx(dot)net> |
Subject: | RE: Happy column adding (was RE: [HACKERS] Happy column dropping) |
Date: | 2000-01-26 11:05:00 |
Message-ID: | 001101bf67ed$304372e0$2801007e@tpf.co.jp |
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> -----Original Message-----
> From: hannu(at)hu(dot)tm(dot)ee [mailto:hannu(at)hu(dot)tm(dot)ee]On Behalf Of Hannu Krosing
>
> Hiroshi Inoue wrote:
> >
> > > However, heap_getattr still won't see the default since it simply
> > > checks to see of the attribute number falls off the end of the
> > > tuple and then returns null.
> > >
> >
> > Sorry,the following question might be already answered but too
> > many postings for me.
> >
> > Do we have to refer default value for already inserted rows ?
> > Doesn't 'default' have its meaning only when rows are about to be
> > inserted ?
>
Oh,I found it from Ross's posting.
General Rules
1) The column defined by the <column definition> is added to T.
2) Let C be the column added to T. Every value in C is the default
value for C.
Note: The default value of a column is defined in Subclause 11.5,
"<default clause>"
Is this reasonable ?
.
> I think the case was about adding a NOT NULL column and setting
> current NULL
> columns to DEFAULT seemed like a natural thing to do.
>
> But, considering the fact that DEFAULT can be something reaaly
> complex, like
> function that does a lot of things, it may be better to have the
> constraints
> checked at the end of transaction, like
>
> BEGIN;
> ALTER TABLE T1 ADD COLUMN C1 TEXT NOT NULL;
Isn't 'iNITIALLY DEFERRED' needed ?
ALTER TABLE T1 ADD COLUMN C1 TEXT NOT NULL INITIALLY DEFERRED;
> UPDATE T1 SET C1='MYDEFAULTVALUE';
> COMMIT;
>
It seems more reasonable than standard.
But is it worth breaking SQL standard ?
Regards.
Hiroshi Inoue
Inoue(at)tpf(dot)co(dot)jp
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