Amdb: A Design Tool for Access Methods

Designing and tuning access methods (AMs) has always been more of a black art than a rigorous discipline, with performance assessments being mostly reduced to presenting aggregate runtime or I/O numbers. This paper presents amdb, a comprehensive graphical design tool for AMs that are constructed on top of the Generalized Search Tree abstraction. At the core of amdb lies an an analysis framework for AMs that defines performance metrics that are more useful than traditional summary numbers and thereby allow the AM designer to detect and isolate deficiencies in an AM design. Amdb complements the analysis framework with visualization and debugging functionality, allowing the AM designer to investigate the source of those deficiencies that were brought to light with the help of the performance metrics. Several AM design projects undertaken at U.C.Berkeley have confirmed the usefulness of theion. At the core of amdb lies an an analysis framework for AMs that defines performance metrics that are more useful than traditional summary numbers and thereby allow the AM designer to detect and isolate deficiencies in an AM design. Amdb complements the analysis framework with visualization and debugging functionality, allowing the AM designer to investigate the source of those deficiencies that were brought to light with the help of the performance metrics. Several AM design projects undertaken at U.C.Berkeley have confirmed the usefulness of the analysis framework and its integration with visualization facilities in amdb. The analysis process that produces the performance metrics is fully automated and takes a workload—a tree and a set of queries—as input; the metrics characterize the performance of each query as well as that of the tree structure. Central to the framework is the use of the optimal behavior—which can be approximated relatively efficiently—as a point of reference against which the actual observed performance is compared. The framework applies to most balanced tree-structured AMs and is not restricted to particular types of of data or queries.