Patent ID: 8799272

Claim:
A data-processing system comprising: a hardware platform that includes two or more processors; and a database-management system that executes a join operation, carried out on two tables R and S that each has rows with one or more join-attribute values, on the two or more processors by on each processor, executing a first portion of the join operation by joining a first subset of the rows of table R, the join-attribute-value distribution of which is skewed above a skew threshold and which have been distributed among the two or more processors by a first distribution method, with a first subset of the rows of table S; and executing a second portion of the join operation by joining a second subset of the rows of table R, the join-attribute-value distribution of which is not skewed or is skewed below a threshold value and which have been distributed among the two or more processors by a second distribution method, with a second subset of the rows of table S; in which the skew threshold is determined by dividing an operator cardinality by the number of processors used during the join operations, deriving a quotient there from, and multiplying the derived quotient by an adjustment factor.