Re: More ADD CONSTRAINT behaviour questions

"Christopher Kings-Lynne" <chriskl@familyhealth.com.au> writes:
>> 1. A non-unique index is already defined over (a, b)
>> 
>> - Either add new index or promote existing one to unique?

> Promoting is in my too-hard basket, so I will simply add a new unique index?
> Too bad if it slows them down, as they should know better?  Should I issue a
> NOTICE warning them that they have overlapping indices?

Seems reasonable.  I suppose dropping the old index wouldn't be a good
idea ;-)

> The other issue is that I'm not sure how much argument checking I should do
> in my code, and how much I should leave for DefineIndex?

I'd say there's no value in expending code space on duplicated error
checks --- *unless* you can give a more specific/appropriate error
message than DefineIndex would.
        regards, tom lane