Summary Data
Aggregate Navigator
An aggregate navigator rewrites queries to use aggregate tables instead of base tables, where possible. All transparent to the end-user.
SQL-Server has "indexed views", which does similar thing inside the RDBMS, but are meant to be unreliable (see below).
Problem: The Ralph-Kimball idea seems to not be 100% reliable, ie., eg. a query clause like "SUM(IF(amount>10,1,0)) AS over_ten" would give the *wrong* answer if rewritten to use the aggregate table. -- So either you have to put up with this, or have a reasonably subtle query-rewriter.
Aggregate Navigation With (Almost) No Metadata - Ralph Kimball [dbmsmag.com]
Indexed Views
Seem to be a feature of SQL-Server standard edition, which let the server return results for group-by queries very quickly.
SQL Server Indexed Views: Too much of a good thing? [terris.com] (Aug 04) -- discussion of MS-SQL indexed views, & why so useful in a d-warehouse (& as a reason against MySql).