From: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
---|---|
To: | Hiroshi Inoue <Inoue(at)tpf(dot)co(dot)jp> |
Cc: | Christopher Kings-Lynne <chriskl(at)familyhealth(dot)com(dot)au>, Hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: BETWEEN Node & DROP COLUMN |
Date: | 2002-07-04 00:38:04 |
Message-ID: | 200207040038.g640c4F28847@candle.pha.pa.us |
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Lists: | pgsql-hackers |
Hiroshi Inoue wrote:
> Bruce Momjian wrote:
> >
> > Hiroshi Inoue wrote:
> > > > As I remember, Hiroshi's drop column changed the attribute number to a
> > > > special negative value, which required lots of changes to track.
> > >
> > > ??? What do you mean by *lots of* ?
> >
> > Yes, please remind me. Was your solution renumbering the attno values?
>
> Yes though I don't intend to object to Christopher's proposal.
>
> > I think there are fewer cases to fix if we keep the existing attribute
> > numbering and just mark the column as deleted. Is this accurate?
>
> No. I don't understand why you think so.
With the isdropped column, you really only need to deal with '*'
expansion in a few places, and prevent the column from being accessed.
With renumbering, the backend loops that go through the attnos have to
be dealt with.
Is this correct? I certainly prefer attno renumbering to isdropped
because it allows us to get DROP COLUMN without any client changes, or
at least with fewer because the dropped column has a negative attno. Is
this accurate?
--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 853-3000
+ If your life is a hard drive, | 830 Blythe Avenue
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