Materialized Sample Views for Database Approximation
Sample views created from the database tables are useful in many applications for reducing retrieval time. A sample view is an indexed materialized view that permits efficient sampling from an arbitrary range query over the view. Such “sample views” are very useful in applications that require random samples from a database: Approximate query processing, online aggregation, data mining, and randomized algorithms are a few examples. The Appendability, Combinability, and Exponentiality (ACE) Tree is a new file organization technique that is suitable for organizing and indexing a sample view. One of the most important aspects of the ACE Tree is that it supports online random sampling from the view. That is, at all times, the set of records returned by the ACE Tree constitutes a statistically random sample of the database records satisfying the relational selection predicate over the view. KeywordsACE Tree, Materialized View, Query Processing.