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.
