Archives of the TeradataForum
Message Posted: Fri, 20 Feb 2009 @ 23:06:03 GMT
David Curley wrote:
Only a Teradata developer could answer that.
I think all those OLAP functions are implemented the same way, which can be seen in explain:
Rows are put into a spool and then redistributed into a second spool based on the PARTITION and ORDER BY columns.
But RANK got some special optimization, that's why it might be faster, especially when there are lots of rows per PARTITION.
You'd better test some variations and then check DBQL data.
|Copyright 2016 - All Rights Reserved|
|Last Modified: 27 Dec 2016|