SQL join elimination

摘要

A method of preventing execution of unnecessary joins between tables in a database is described. A Structured Query Language (SQL) statement is presented to the database. The SQL statement has a scope that extends to a set of tables in the database and returns a set of results from the database. A list of tables that are within the scope of the SQL statement but that are not referred to by the SQL statement is prepared. Tables that must be accessed in order to return the set of results are removed from the list in accordance with a predetermined set of rules. The execution of joins involving any of the tables remaining in the list is prevented.