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Abstract

A method is provided for parallel and cooperative processing of data in a system wherein a coordinator process cooperates with one or more agent processes to which portions of the data processing function is off loaded. The agent processes read and process the data and accumulate a partial result. Each agent process, responsive to statistics collected on the content of the data processed, returns a partial result of the processing to the coordinator process. These steps are repeated iteratively until the processing has been completed. In a specific application, the performance of data processing systems is improved by speeding up database group-by queries. The group-by operation processing is distributed between the host central processing unit (CPU) and the input/output (I/O) processors (IOPs). Essentially, the IOPs are sent group-by requests to be performed on a set of disk blocks (extents), along with a predicate for tuples to be selected for query. The IOPs build a hash table with entries of the group-by element and a running aggregation function (sum for example). The IOPs retrieve the extents, extract the records, select records using the predicate specified, enter the element in the hash table if it is not already there, and perform the corresponding aggregation function.

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First Claim