Patent ID: 9672248
Date: 2017-06-06
CPC Classifications: G06F

Claim:
1. A computer program product for performing a join operation in a database, the computer program product comprising a computer readable storage medium having program instructions embodied therewith, the program instructions executable by a processor to cause the processor to perform: during a query optimization for a query involving a join operation, obtaining a distribution of data values in a join column of an inner table; using the distribution, identifying one or more data ranges containing skew; performing a cost-benefit analysis for a skew specific join scheme, wherein the cost benefit analysis is based on a tradeoff between a number of the data values in a data range of the one or more data ranges and additional overhead costs of processing the number of data values using the skew specific join scheme; for each data range identified as containing skew, performing, by the processor, the join operation using the skew specific join scheme based on the cost-benefit analysis; and for each data range not identified as containing skew, performing, by the processor, the join operation using a non-skew specific join scheme.