Abstract: A method, system, and computer program product for planning relational database joins in systems with multiple parallel computational units. The computer implemented method compiles an execution plan for dissemination to a plurality of execution units where the plan combines a smaller left-side table with a portion of a larger right-side object to reduce system overhead. Upon receiving a request for a join operation comprising left-side table data and right-side table data where the left-side table data is much smaller than the right-side table data, then the method compiles a plan to apportion an entirety of the left-side table data and only a portion of the right-side object to a plurality of computational units. The method continues by sending distribution instructions to respective computational units where the distribution instructions include retrieval of the entirety of the left-side table data with the retrieval of only a portion of the right-side object.

Abstract: A method, system, and computer program product for planning relational database joins in systems with multiple parallel computational units. The computer implemented method compiles an execution plan for dissemination to a plurality of execution units where the plan combines a smaller left-side table with a portion of a larger right-side object to reduce system overhead. Upon receiving a request for a join operation comprising left-side table data and right-side table data where the left-side table data is much smaller than the right-side table data, then the method compiles a plan to apportion an entirety of the left-side table data and only a portion of the right-side object to a plurality of computational units. The method continues by sending distribution instructions to respective computational units where the distribution instructions include retrieval of the entirety of the left-side table data with the retrieval of only a portion of the right-side object.

Abstract: A method, system, and computer program product for high-performance database systems. The method commences by estimating, during a compile phase, a statically-calculated system cost of performing parallel join operations over two relations, then selecting, during the compile phase, a first distribution method to perform the parallel join operations. Instructions (e.g., table partitioning) are communicated to two or more execution units for execution of the parallel join operations, and during execution, various measurements are taken pertaining to the performance of a first portion of the parallel join operations using the selected first distribution method. Then, responsive to the measurements a second distribution method is selected and corresponding instructions are communicated to the two or more execution units. The parallel join operations continue, now using the second distribution method.