document: Schema evolution in data warehouses We address the issues related to the evolution and maintenance of data warehousing systems , when underlying data sources change their schema capabilities . These changes can invalidate views at the data warehousing system . We present an approach for dynamically adapting views according to schema changes arising on source relations . This type of maintenance concerns both the schema and the data of the data warehouse . The main issue is to avoid the view recomputation from scratch especially when views are defined from multiple sources . The data of the data warehouse is used primarily in organizational decision-making and may be strategic . Therefore , the schema of the data warehouse can evolve for modeling new requirements resulting from analysis or data-mining processing . Our approach provides means to support schema evolution of the data warehouse independently of the data sources
doc_bio_tags: B I O B I O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O B I
extractive_keyphrases: schema evolution data warehouses data sources source relations
abstractive_keyphrases: system maintenance containment structural view maintenance view adaptation sql query organizational decision-making data analysis