Data Cube: A Relational Aggregation Operator Generalizing Group-By, Cross-Tab, and Sub-Totals
Data Mining and Knowledge Discovery
QC-trees: an efficient summary structure for semantic OLAP
Proceedings of the 2003 ACM SIGMOD international conference on Management of data
Incremental maintenance of quotient cube for median
Proceedings of the tenth ACM SIGKDD international conference on Knowledge discovery and data mining
Quotient cube: how to summarize the semantics of a data cube
VLDB '02 Proceedings of the 28th international conference on Very Large Data Bases
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This paper introduces a new kind of bitmap index. A tuple in the data cube is mapped to a sequential key (seqkey) determined by its value in each dimension. Furthermore, the quotient bit sequence is constructed according to whether the corresponding cell of a seqkey exists in the cover quotient cube or not, and the cover quotient cube is indexed by this quotient bit sequence (qcbit index). A compression method is presented for the seqkey cover quotient cube, which compress the cover quotient cube via omitting dimension attributes for all cells. To improve the storage and query of data cubes, based on these index and compression methods, algorithms are proposed to query the cover quotient cube and seqkey cover quotient cube. Experimental results on the dataset weather show that the volume of the qcbit index file is only 11% of the value-list index file, and the volume of seqkey cover quotient cube is only 27.75% of the original cover quotient cube.