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Posted to dev@parquet.apache.org by "Alex Levenson (JIRA)" <ji...@apache.org> on 2014/07/24 08:32:38 UTC

[jira] [Created] (PARQUET-42) Add HyperLogLog / CountMinSketch to parquet statistics

Alex Levenson created PARQUET-42:
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             Summary: Add HyperLogLog / CountMinSketch to parquet statistics
                 Key: PARQUET-42
                 URL: https://issues.apache.org/jira/browse/PARQUET-42
             Project: Parquet
          Issue Type: New Feature
          Components: parquet-mr
            Reporter: Alex Levenson
            Priority: Minor


HLL and CMS for rowgroups could help with query planning (getting a sense of data skew) and with cheaply counting approximate distinct values. Both are commutative which means they can be combined across rowgroups (unlike an exact distinct count for example).



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