WinMagic: Subquery Elimination Using Window Aggregation
Calisto Zuzarte, Hamid Pirahesh, et al.
SIGMOD 2003
Automatic Summary Tables (ASTs), more commonly known as materialized views, are widely used to enhance query performance, particularly for aggregate queries. Such queries access a huge number of rows to retrieve aggregated summary data while performing multiple joins in the context of a typical data warehouse star schema. To keep ASTs consistent with their underlying base data, the ASTs are either immediately synchronized or fully recomputed. This paper proposes an optimization strategy for simultaneously refreshing multiple ASTs, thus avoiding multiple scans of a large fact table (one pass for AST computation). A query stacking strategy detects common sub-expressions using the available query matching technology of DB2. Since exact common sub-expressions are rare, the novel query sharing approach systematically generates common subexpressions for a given set of "related" queries, considering different predicates, grouping expressions, and sets of base tables. The theoretical framework, a prototype implementation of both strategies in the IBM DB2 UDB/UWO database system, and performance evaluations based on the TPC/R data schema are presented in this paper.
Calisto Zuzarte, Hamid Pirahesh, et al.
SIGMOD 2003
Jim Gray, Surajit Chaudhuri, et al.
Data Mining and Knowledge Discovery
Wolfgang Lehner, Richard Sidle, et al.
SIGMOD Record (ACM Special Interest Group on Management of Data)
Kevin Beyer, Roberta J. Cochrane, et al.
SIGMOD 2005