On Tue, 2009-05-19 at 12:17 +0100, Matthew Wakeling wrote:
> Yes, Postgres has been missing the boat on this one for a while. +1 on
> requesting this feature.
That's an optimizer feature.
> Speaking of avoiding large sorts, I'd like to push again for partial
> sorts. This is the situation where an index provides data sorted by
> column "a", and the query requests data sorted by "a, b". Currently,
> Postgres sorts the entire data set, whereas it need only group each
> set of identical "a" and sort each by "b".
This is an executor feature.
Partially sorted data takes much less effort to sort (OK, not zero, I
grant) so this seems like a high complexity, lower value feature. I
agree it should be on the TODO, just IMHO at a lower priority than some
other features.
--
Simon Riggs www.2ndQuadrant.com
PostgreSQL Training, Services and Support