System, method, and computer-readable medium for reducing row redistribution costs for parallel join operations

A non-transitory computer-readable medium having computer-executable instructions for execution by a processing system, the computer-executable instructions for optimizing a join operation in a parallel processing system, the computer-executable instructions, when executed, cause the processing system to:

• identify a plurality of processing nodes that have at least one row of one or more tables involved in a join operation;
• for each of the processing nodes, determine respective counts of rows that would be redistributed to each of the processing nodes based on join attributes of the rows;
• calculate a redistribution matrix from the counts of rows of each of the processing nodes;
• and
• generate an optimized redistribution matrix from the redistribution matrix, wherein the optimized redistribution matrix provides a minimization of rows to be redistributed among the nodes to execute the join operation.

A database management system, comprising:

• a plurality of processing nodes each including at least one respective processing module;
• at least one storage device to which a respective set of rows of a first table and a second table involved in a join operation are allocated to each of the plurality of processing modules, wherein the join operation comprises a join on a column of the first table and a column of the second table;
• and
• an optimizer that identifies a plurality of processing nodes that have at least one row of one or more tables involved in the join operation, determines respective counts of rows that would be redistributed to each of the processing nodes based on join attributes of the rows for each of the processing nodes;
• calculates a redistribution matrix from the counts of rows of each of the processing nodes, and generates an optimized redistribution matrix from the redistribution matrix, wherein the optimized redistribution matrix provides a minimization of rows to be redistributed among the nodes to execute the join operation.