EXPLOITING EXECUTION FEEDBACK FOR OPTIMIZING CHOICE OF ACCESS METHODS

摘要

A proactive monitoring mechanism for correcting the choice of access methods (available query plans) for a given query, based on execution feedback from the same query. The mechanism exploits bypassing predicate short-circuiting inside the database server's predicate evaluation module to obtain expression cardinalities. The mechanism can also modify a plan to obtain expression cardinalities. These techniques are used judiciously by the query optimizer and/or a database administrator (DBA) so that the execution overheads are within acceptable limits.