Dynamic Cubes for OLAP Data Updates

F. Sha and T. Furukawa (Japan)

Keywords

Range-sum query, Data cube, OLAP

Abstract

Range-sum queries are powerful tool for analyzing trends and relationships between attributes. They add up the val ues of the selected cells in specified ranges of an OLAP data cube. Since the response time is very crucial for users, the prefix sum approach is proposed to evaluate any range sum query at a constant cost. However, the update cost of this method is on the order of the size of the data cube. Re building the entire data cube may be very costly and is not realistic because the size of a data cube is exponential in the number of its dimensions. The dynamic update cube approach provides an algorithm to reduce the update cost while maintaining reasonable cost to evaluate the range sum query. If there are no update data in some range, range sum queries on this range can be evaluated without access ing the dynamic update cube. In this paper, we propose new methods that clean up ranges which are frequently used to evaluate range-sum queries. The additional cost to access the dynamic update cube for query evaluation can be cut down and the cost of query evaluation on these ranges is equal to the prefix sum model.

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