Re: BETWEEN Node & DROP COLUMN

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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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
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