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 9558.1072074514@sss.pgh.pa.us
Whole thread Raw
In response to cascading column drop to index predicates  (Christopher Kings-Lynne <chriskl@familyhealth.com.au>)
Responses Re: cascading column drop to index predicates
List pgsql-hackers
Christopher Kings-Lynne <chriskl@familyhealth.com.au> writes:
> The thing is, if you drop a column that is used in a normal index, yes 
> the index is now useless - drop it.
> However, since you can have (and I have) indexes like this:
> CREATE INDEX asdf ON table (a, b, c) WHERE d IS NOT NULL;
> If I drop column d, there is no way I want that index to just disappear!

Uh, why not?  I don't quite see the argument why d stands in a different
relationship to this index than a,b,c do.  The index is equally
meaningless without any of them.

> Can we change it to requiring a CASCADE?

It'd likely be a simple code change, but first let's have the argument
why it's a good idea.
        regards, tom lane


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