Re: cascading column drop to index predicates

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Rod Taylor <pg(at)rbt(dot)ca>
Cc: Andreas Pflug <pgadmin(at)pse-consulting(dot)de>, Christopher Kings-Lynne <chriskl(at)familyhealth(dot)com(dot)au>, PostgreSQL Development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: cascading column drop to index predicates
Date: 2003-12-22 16:08:06
Message-ID: 16404.1072109286@sss.pgh.pa.us
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Rod Taylor <pg(at)rbt(dot)ca> writes:
> I think Andreas is trying to argue that if you drop column b from index
> (a, b) that the index should be converted into index(a) -- assuming of
> course there isn't already an index(a).

That seems to be well outside the charter of DROP CASCADE. I think we
either drop or don't drop; we don't go building new indexes, which is
what this would take. There are also definitional problems --- for
instance, if the index is UNIQUE, does it transmogrify into a UNIQUE
constraint on A alone (which would most likely fail)?

regards, tom lane

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