On Wed, Oct 5, 2016 at 9:04 AM, Amit Kapila <amit.kapil...@gmail.com> wrote: > Okay, but in that case I think we don't need to store including > columns in non-leaf pages to get the exact ordering. As mentioned > upthread, we can use truncated scan key to reach to leaf level and > then use the complete key to find the exact location to store the key. > This is only possible if there exists an opclass for columns that are > covered as part of including clause. So, we can allow "order by" to > use index scan only if the columns covered in included clause have > opclass for btree.
But what if there are many pages full of keys that have the same values for the non-INCLUDING columns? -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
