TY - JOUR
AU - Joshi, Milind
AB -  Orthogonal Optimization of Subqueries and Aggregation Cesar A. Galindo-Legaria ´ Microsoft Corp. One Microsoft Way Redmond, WA 98052 Milind M. Joshi {cesarg,milindj}@microsoft.com ABSTRACT There is considerable overlap between strategies proposed for subquery evaluation, and those for grouping and aggregation. In this paper we show how a number of small, independent primitives generate a rich set of e ƒcient execution strategies ”covering standard proposals for subquery evaluation suggested in earlier literature. These small primitives fall into two main, orthogonal areas: Correlation removal, and e ƒcient processing of outerjoins and GroupBy. An optimization approach based on these pieces provides syntaxindependence of query processing with respect to subqueries, i. e. equivalent queries written with or without subquery produce the same e ƒcient plan. We describe techniques implemented in Microsoft SQL Server (releases 7.0 and 8.0) for queries containing subqueries and/or aggregations, based on a number of orthogonal optimizations. We concentrate separately on removing correlated subqueries, also called œquery ‚attening,  and on e ƒcient execution of queries with aggregations. The end result is a modular, ‚exible implementation, which produces very e ƒcient execution plans. To demonstrate the validity of our approach, we present results for some queries from the TPC-H benchmark. 
TI - Orthogonal optimization of subqueries and aggregation
DO - 10.1145/375663.375748
DA - 2001-05-01
UR - https://www.deepdyve.com/lp/association-for-computing-machinery/orthogonal-optimization-of-subqueries-and-aggregation-M8KYM0SWL1
DP - DeepDyve
ER -