real time self-maintenable data warehouse
Data warehousing is an approach to data integration wherein integrated information is stored in a data warehouse for direct querying and analysis. To provide fast access, a data warehouse stores materialized views of the sources of its data. As a result, a data warehouse needs to be maintained to keep its contents consistent with the contents of its data sources. Incremental maintenance is generally regarded as a more efficient way to maintain materialized views in a data warehouse. In this paper a strategy for the maintenance of data warehouse is presented. It has the following characteristics: it is self-maintainable (weak), incremental, non-blocking (the analysts transactions and the maintenance transaction are executed concurrently) and is performed in real time. The proposed algorithm is implemented for view definition SPJ (Select Project Join) queries and it calculates the aggregate functions: sum, avg, count, min and max. Aggregate functions are calculated like algebraic functions (the new result of the function can be computed using some small, constant size storage that accompanies the existing value of the aggregate). We have named this improved algorithm ?VNLTR (unlimited ?V (versions), NL (non-blocking), TR (in real time)).
self-maintenable data warehouse