Now that there are index only scans, there is a use case for having a composite index which has the primary key or a unique key as the prefix column(s) but with extra columns after that. Currently you would also need another index with exactly the primary/unique key, which seems like a waste of storage and maintenance.
Should there be a way to declare a "unique" index with the unique property applying to a prefix of the indexed columns/expression? And having that, a way to turn that prefix into a primary key constraint? Of course this is easier said then done, but is there some reason for it not to be a to-do item? Thanks, Jeff -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
