Re: Materialized views and unique indexes

Craig Ringer <craig@2ndquadrant.com> writes:
> On 03/08/2013 10:55 AM, Michael Paquier wrote:
>> Also, as it is not mandatory for a unique index to be a constraint, I
>> think that we should block the creation of unique indexes too to avoid
>> any problems. Any suggestions?

> How much does the planner benefit from the implied constraint of a
> unique index? I almost wonder if it should be allowed at the cost of
> making the refresh of a matview that fails to comply an error.

A unique constraint can allow join elimination, so I'm thinking that
disallowing them is a bad idea (not to mention that it'd be a
considerable wart in the code to block them for matviews only).
        regards, tom lane