345-357 Eager Aggregation and Lazy Aggregation. Abstract Efficient processing of aggregation queries is essential for decision support applications. This paper describes a class of query transformations, called eager aggregation and lazy aggregation , that allows a query optimizer tomove group-by operations up and down the query tree. Eager aggregation partially pushes a group-by past a join. Eager aggregation reduces the number of input rows to the join and thus may result in a better overall plan.
Experimental results show that the technique is very beneficial for queries in the TPC-D benchmark.
Permission to copy without fee all or part of this material is granted provided that the copies are not made or distributed for direct commercial advantage, the VLDB copyright notice and the title of the publication and its date appear, and notice is given that copying is by the permission of the Very Large Data Base Endowment. Including Group-By in Query Optimization. Performing Group-By before Join. A Framework for Statistical Data Mining with Summary Tables. Simultaneous Optimization and Evaluation of Multiple Dimensional Queries.