DVH: a query processing method using domain vectors and hashing

Abstract

The authors introduce a fast, space-efficient technique for accelerating equijoins between very large relations. The technique, called Domain Vector Hash (DVH) join Acceleration, is described and compared with three other join accelerators: hybrid-hash, join indexes, and materialized views. An analytic cost model is developed for each join method, and a detailed analytic performance comparison is made between each technique. The results show that DVH-join produces much faster joins than any of the other techniques considered, and over a considerably wider range of join selectivities and memory sizes. Moreover, the approach achieves this performance improvement while simultaneously minimizing the amount of additional join information that is cached on disk. When compared with either join indexes or materialized views, DVH typically requires from one to four orders of magnitude less cache space.<>