System, method, and computer-readable medium for optimizing processing of queries featuring maximum or minimum equality conditions in a parallel processing system

摘要

A system, method, and computer-readable medium for optimized processing of queries that feature maximum or minimum equality conditions are provided. A table on which the query is applied is scanned a single time. Rows of the table distributed to respective processing modules are scanned by the processing modules. Each processing module maintains identification of any rows distributed to the respective processing module that have attribute values that equal the maximum or minimum attribute value locally identified by the processing module. Subsequently, a global aggregation mechanism is invoked to compute the query result without requiring an additional rescan of the table. Further, the disclosed mechanisms may be extended to compute top N queries featuring maximum or minimum equality conditions.