Fundamentals of database systems (2nd ed.)
Fundamentals of database systems (2nd ed.)
Proceedings of the eighth international conference on Information and knowledge management
Data Cube: A Relational Aggregation Operator Generalizing Group-By, Cross-Tab, and Sub-Totals
Data Mining and Knowledge Discovery
The MD-join: An Operator for Complex OLAP
Proceedings of the 17th International Conference on Data Engineering
Using SQL to Build New Aggregates and Extenders for Object- Relational Systems
VLDB '00 Proceedings of the 26th International Conference on Very Large Data Bases
Querying Multiple Features of Groups in Relational Databases
VLDB '96 Proceedings of the 22th International Conference on Very Large Data Bases
Evaluation of Ad Hoc OLAP: In-Place Computation
SSDBM '99 Proceedings of the 11th International Conference on Scientific and Statistical Database Management
User Defined Aggregates in Object-Relational Systems
ICDE '00 Proceedings of the 16th International Conference on Data Engineering
Measurement and analysis of IP network usage and behavior
IEEE Communications Magazine
Efficient OLAP query processing in distributed data warehouses
Information Systems - Special issue: Best papers from EDBT 2002
Efficient OLAP Query Processing in Distributed Data Warehouses
EDBT '02 Proceedings of the 8th International Conference on Extending Database Technology: Advances in Database Technology
Partitioned optimization of complex queries
Information Systems
Using grouping variables to express complex decision support queries
Data & Knowledge Engineering
SQL query optimization through nested relational algebra
ACM Transactions on Database Systems (TODS)
θ-Constrained multi-dimensional aggregation
Information Systems
Supporting real-time supply chain decisions based on RFID data streams
Journal of Systems and Software
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On-line analytical processing (OLAP) has become an increasingly important concern for telecommunications operators. Telecommunications systems generate huge amounts of data that would be beneficial to analyze using OLAP technology. Recently, Chatziantoniou et al. [4] presented the MD-join, a relational operator that provides a clean separation between group definitions and aggregate computations, and allows to succinctly express OLAP queries. In this paper, we define generalized MD-joins, describe an implementation of the GMD-join query engine on top of a commercial DBMS, and present a reduction of GMD-joins to SQL. We present a practical new optimization of GMD-joins allowing the restriction of base-values, and discuss the optimization of GMD-joins with restrictions and coalescing of GMD-joins. We show how GMD-join optimizations can be used to improve the performance of the translated SQL queries. Finally, we present experiments comparing the GMD-join query engine with the SQL reduction.