Rewriting a query in terms of a summary based on aggregate computability and canonical format, and when a dimension table is on the child side of an outer join

摘要

A method and system are provided for processing queries, where the queries do not reference a particular materialized view. Specifically, techniques are provided for handling a query that specifies a first set of one or more aggregate functions, where the particular materialized view reflects a second set of one or more aggregate functions. Whether the query can be rewritten is determined based on the aggregate functions in the first and second sets, and the corresponding arguments. Techniques are also provided for processing a query that (1) does not reference a particular materialized view, (2) specifies a first set of one or more aggregate functions, where the particular materialized view reflects a second set of one or more aggregate functions. A technique is also provided for rewriting queries that specify an outer join that has a dimension table on the child-side of the outer join and a fact table on the parent-side of the outer join. The query is rewritten to produce a rewritten query by replacing references to the fact table in the query with references to a materialized view. The rewritten query specifies an outer join that has the dimension table on the child side and the materialized view on the parent side.