A relational database warehouse system with query optimization capabilities is described that allows for speedy identification of sets of records of interest from amongst tens of millions of records. The records of interest may include complex derived attributes, generated, at least in part, by aggregating data from a plurality of records in base data tables. In various embodiments, the query optimization capabilities allow the database warehouse system to identify conditions under which normal query execution may be replaced by one or more optimized execution methods, including, for example, eliminating unnecessary inner join operations on base data tables specified by a query, re-ordering the execution of group-by operations and left-outer join operations to greatly reduce the size of join tables produced while processing a query, and/or consolidating a set of segmentation queries for execution in one pass over the records of the database.