Re: ALTER TABLE DROP COLUMN - Mailing list pgsql-hackers

From Hannu Krosing
Subject Re: ALTER TABLE DROP COLUMN
Date
Msg-id 39E2F72B.9CFFE99E@tm.ee
Whole thread Raw
In response to Re: ALTER TABLE DROP COLUMN  (The Hermit Hacker <scrappy@hub.org>)
List pgsql-hackers
The Hermit Hacker wrote:
> 
> On Mon, 9 Oct 2000, Bruce Momjian wrote:
> 
> Ya, but in one email, you appear to agree with me ... then Tom posts a
> good point and you jump over to that side ... at least pick a side? :)  I
> too wish to see it implemented, I just don't want to have to double my
> disk space if at some point I decide to upgrade an application and find
> out that they decided to change their schema(s) :(

As Don already pointed out, if you don't have enough room to double your 
table size you must be running an one-table, append-only application where 
you can only do a very limited set of queries. 

select * from that_table order by some_column_without_an_index; is definitely 
out as it takes many times the space of a that_table anyway.

There _may_ be some cases where 2x is unacceptable, but without radically 
changing tables on-disk structure there is no way to avoid it and still be 
able to rollback or even crash cleanly ;)

-----------------
Hannu


pgsql-hackers by date:

Previous
From: Jeff MacDonald
Date:
Subject: Re: Announcing PgSQL - a Python DB-API 2.0 compliant interface to PostgreSQL
Next
From: Bruce Momjian
Date:
Subject: Re: CVS broken?