On Wed, Oct 5, 2016 at 9:04 AM, Amit Kapila <amit.kapila16@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
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