Re: BETWEEN Node & DROP COLUMN

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Rod Taylor <rbt(at)zort(dot)ca>, Thomas Lockhart <lockhart(at)fourpalms(dot)org>, Christopher Kings-Lynne <chriskl(at)familyhealth(dot)com(dot)au>, Hiroshi Inoue <Inoue(at)tpf(dot)co(dot)jp>, Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: BETWEEN Node & DROP COLUMN
Date: 2002-07-05 00:03:43
Message-ID: 200207050003.g6503hp06539@candle.pha.pa.us
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Tom Lane wrote:
> Rod Taylor <rbt(at)zort(dot)ca> writes:
> >> We could change pg_attribute to another name, and create a view called
> >> pg_attribute that never returned isdropped columns to the client. That
> >> would allow clients to work cleanly, and the server to work cleanly.
>
> > Another case where having an informational schema would eliminate the
> > whole argument -- as the clients wouldn't need to touch the system
> > tables.
>
> This is a long-term solution, not a near-term one. I suspect it's
> really unlikely that pg_dump, pgAdmin, etc will ever want to switch
> over to the SQL-standard informational schema, because they will want
> to be able to look at Postgres-specific features that are not reflected
> in the standardized schema. Certainly there will be no movement in
> that direction until the informational schema is complete; a first-cut
> implementation won't attract any interest at all :-(
>
> I thought about the idea of a backward-compatible pg_attribute view,
> but I don't see any efficient way to generate the consecutively-numbered
> attnum column in a view; anyone?

No, we can't, and because our client coders want consecutive, it is a
dead idea. Even if we could do it, we would be feeding clients attno
values that are inaccurate, causing problems when attno is joined to
other tables.

--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 853-3000
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