On Fri, Jun 14, 2013 at 06:28:06PM -0400, Alvaro Herrera wrote: > Partial indexes are not supported; since an index is concerned with minimum > and > maximum values of the involved columns across all the pages in the table, it > doesn't make sense to exclude values.
It can make sense if the predicate references a column other than the indexed column(s). Unlike a partial btree index, a partial minmax index would be no smaller. It could have narrower min-max spreads, reducing the recheck work done by queries. > Another way to see "partial" indexes > here would be those that only considered some pages in the table instead of > all > of them; but this would be difficult to implement and manage and, most likely, > pointless. That's a distinct feature from the AM-independent partial index mechanism, in any event. > Expressional indexes can probably be supported in the future, but we disallow > them initially for conceptual simplicity. Whether an index column uses an expression is irrelevant to each existing core AM. How does minmax differ in this respect? Thanks, nm -- Noah Misch EnterpriseDB http://www.enterprisedb.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
