On Tuesday, January 5, 2016, Steve Rogerson <
steve.pg@yewtc.demon.co.uk> wrote:
On 05/01/16 19:47, Tom Lane wrote:
> Steve Rogerson <steve.pg@yewtc.demon.co.uk> writes:
>> Is this a bug? I create a "unique" index, directly but it doesn't add a unique
>> constraint. Add a unique constraint and it adds the index and the constraint.
>
> That's operating as designed. A unique constraint needs an index,
> but not vice versa.
I can see that might be plausible , hence the question but as a "unique index"
imposes as constraint they seem equivalent. What's the functional difference
between the two situations?
I suspect it has to do with partial unique indexes.
David J.