Answering queries using views (extended abstract)
PODS '95 Proceedings of the fourteenth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
Implementing data cubes efficiently
SIGMOD '96 Proceedings of the 1996 ACM SIGMOD international conference on Management of data
Maintenance of data cubes and summary tables in a warehouse
SIGMOD '97 Proceedings of the 1997 ACM SIGMOD international conference on Management of data
The TSQL2 Temporal Query Language
The TSQL2 Temporal Query Language
Modelling Large Scale OLAP Scenarios
EDBT '98 Proceedings of the 6th International Conference on Extending Database Technology: Advances in Database Technology
A Logical Approach to Multidimensional Databases
EDBT '98 Proceedings of the 6th International Conference on Extending Database Technology: Advances in Database Technology
VLDB '00 Proceedings of the 26th International Conference on Very Large Data Bases
Change-Centric Management of Versions in an XML Warehouse
Proceedings of the 27th International Conference on Very Large Data Bases
The COMET Metamodel for Temporal Data Warehouses
CAiSE '02 Proceedings of the 14th International Conference on Advanced Information Systems Engineering
Multidimensional Data Modeling for Complex Data
ICDE '99 Proceedings of the 15th International Conference on Data Engineering
Maintaining Data Cubes under Dimension Updates
ICDE '99 Proceedings of the 15th International Conference on Data Engineering
Time in multidimensional databases
Multidimensional databases
XCube: XML for data warehouses
DOLAP '03 Proceedings of the 6th ACM international workshop on Data warehousing and OLAP
Creation and management of versions in multiversion data warehouse
Proceedings of the 2004 ACM symposium on Applied computing
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Commercial OLAP systems usually consider OLAP dimensions as static entities. In practice, dimension updates are often necessary in order to adapt the multidimensional database to changing requirements. Query languages are then needed to retrieve historical information from a data warehouse. Although many proposals addressing temporal OLAP exist, none supports full operation over the World Wide Web. After introducing a temporal data model supporting historical dimensions and fact table versioning, we present a three-tier architecture based on web services, SOAP and XML, allowing efficient querying over the web. In this architecture, XML metadata is stored at the application server in the form of XML documents containing the data warehouse structure. This allows addressing most of the requests (navigation through time, updates and queries) without accessing the data warehouse. In the second part of the paper, we present TOLAP-QL, an SQL-like temporal query language. We describe the syntax and semantics of the language, a sequel of its logic-based predecessor, TOLAP. We study query optimisation in temporal OLAP, and introduce a technique based on materialisation of historical views. Last, but not least, we present a system implementation, and a real-world case study, that shows that our proposal achieves good query performance for OLAP queries over large historical databases in a web environment.