On 5 July 2014 02:03, Vik Fearing <vik.fear...@dalibo.com> wrote: > [1] http://wiki.postgresql.org/wiki/Loose_indexscan
Thanks. It talks about DISTINCT, and also about using index when you don't have the leading column in your WHERE clause (as well as MySQL ("loose"), at least Oracle ("skip"), SQLite ("skip"), DB2 ("jump") can do this). It looks like at least MySQL can also use loose index scans to implement GROUP BY in certain cases involving MIN or MAX aggregate functions (things like SELECT a, MIN(b) FROM foo GROUP BY a, given an index on (a, b)). But I'm only trying to implement the lowest hanging index skipping plan: plain old DISTINCT. I think I see roughly how to cost, plan and execute it... now to learn a lot more about PG internals... -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers