Re: cascading column drop to index predicates - Mailing list pgsql-hackers

From Tom Lane
Subject Re: cascading column drop to index predicates
Date
Msg-id 16404.1072109286@sss.pgh.pa.us
Whole thread Raw
In response to Re: cascading column drop to index predicates  (Rod Taylor <pg@rbt.ca>)
Responses Re: cascading column drop to index predicates  (Andreas Pflug <pgadmin@pse-consulting.de>)
List pgsql-hackers
Rod Taylor <pg@rbt.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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