On 8 July 2016 at 09:49, Robert Haas <robertmh...@gmail.com> wrote: > We're probably missing a few tricks on queries of this type. If the > index-traversal machinery had a mechanism to skip quickly to the next > distinct value, that could be used here: walk up the btree until you > find a page that contains keyspace not equal to the current key, then > walk back down until you find the first leaf page that contains such a > value. That would potentially let you step over large chunks of the > index without actually examining all the leaf pages, which for a query > like this seems like it could be a big win.
Thomas Munro did take some initial steps to implementing this a few years ago: https://www.postgresql.org/message-id/CADLWmXXbTSBxP-MzJuPAYSsL_2f0iPm5VWPbCvDbVvfX93FKkw%40mail.gmail.com -- David Rowley http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
