US 6,546,381 B1 · Query optimization system and method

Abstract

A query optimization system and method are particularly suitable for generating a least cost query plan expressible on a plurality of heterogeneous database schemas that are restructuring views of each other. The query optimization system receives a query against one of the tables and converts it to a plurality of alternate queries, each formatted for the particular schema of a different one of the plurality of heterogeneous tables. In generating the alternate queries, the system may utilize SchemaSQL view definitions and may employ restructuring operators expressing and capable of conducting a restructuring of a table into a restructuring view of the table. A middleware system involving a canonical schema and a virtual canonical table may also be employed to express a mapping between restructuring views for purposes of query conversion. The alternate queries may be costed and optimized and a query plan returned that has a least cost or service time involved.

Claims30

Dependent claims

An apparatus for implementing a database query system, the apparatus comprising:

a processor for executing instructions;
and
a memory device having thereon modules of executable and operational data for execution by the processor, the modules comprising:
a schema mapping module executable on the processor to express a schema mapping between a plurality of heterogeneous database schemas containing at least partially replicated information;
and
a query translation module executable on the processor to communicate with the schema mapping module and translate a received query executable on one of the plurality of heterogeneous database schemas to a substantially equivalent query executable on another of the plurality of heterogeneous database schemas.

3 more elements

Dependencies are inferred from the claim text.

Query optimization system and method

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Query optimization system and method

Life of this patent

Abstract

Claims30