AW: ALTER TABLE DROP COLUMN

From: Zeugswetter Andreas SB <ZeugswetterA(at)wien(dot)spardat(dot)at>
To: "'Tom Lane'" <tgl(at)sss(dot)pgh(dot)pa(dot)us>, The Hermit Hacker <scrappy(at)hub(dot)org>
Cc: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>, Hiroshi Inoue <Inoue(at)tpf(dot)co(dot)jp>, PostgreSQL Development <pgsql-hackers(at)postgreSQL(dot)org>
Subject: AW: ALTER TABLE DROP COLUMN
Date: 2000-10-12 14:23:35
Message-ID: 11C1E6749A55D411A9670001FA68796336809F@sdexcsrv1.f000.d0188.sd.spardat.at
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> WAL would provide the framework to do something like that, but I still
> say it'd be a bad idea. What you're describing is
> irrevocable-once-it-starts DROP COLUMN; there is no way to
> roll it back.
> We're trying to get rid of statements that act that way, not add more.

Yes.

> I am not convinced that a 2x penalty for DROP COLUMN is such a huge
> problem that we should give up all the normal safety features of SQL
> in order to avoid it. Seems to me that DROP COLUMN is only a
> big issue during DB development, when you're usually working with
> relatively small amounts of test data anyway.

Here I don't agree, the statement can also be used for an application version
upgrade. Thus seen in SAP/R3 with tables > 30 Gb.

My conclusion would be that we need both:
1. a fast system table only solution with physical/logical column id
2. a tool that does the cleanup (e.g. vacuum)

Andreas

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