Bifocal Sampling for Skew-Resistant Join Size Estimation

  title={Bifocal Sampling for Skew-Resistant Join Size Estimation},
  author={Sumit Ganguly and Phillip B. Gibbons and Yossi Matias and Abraham Silberschatz},
  booktitle={SIGMOD Conference},
This paper introduces bifocal sampling, a new technique for estimating the size of an equi-join of two relations. Bifocal sampling classifies tuples in each relation into two groups, sparse and dense, based on the number of tuples with the same join value. Distinct estimation procedures are employed that focus on various combinations for joining tuples (e.g., for estimating the number of joining tuples that are dense in both relations). This combination of estimation procedures overcomes some… CONTINUE READING
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