Jeff Janes <jeff.ja...@gmail.com> writes: > 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? Um ... other than it being ugly as sin? I can't say that I can get excited about this concept. It'd be better to work on index-organized tables, which is really more or less what you're wishing for here. Duplicating most of a table into an index is always going to be a loser in the end because of the redundant storage. regards, tom lane -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers