Testing Efficiency and Stability of a Database Query Engine

Systems, methods and computer program products for testing the stability and efficiency of a database query engine are described herein. In an embodiment, all possible query execution plans considered by a query optimizer are retained in the form of abstract plans (APs). Each AP is then subsequently supplied with a query to test for stack traces and incorrect results that may occur during the execution of the query. An embodiment includes determining an optimizer efficiency index (OEI) by comparing each AP with a query execution plan chosen by the query optimizer and classifying the APs into various performance buckets based on the degree of improvement or degradation in performance with respect to the query execution plan chosen by the query optimizer. In another embodiment to determine the optimizer efficiency index, APs are ranked based on estimated cost and classified into a plurality of categories based on query optimizer estimates and actual execution behavior.