Add HyperLogLog / CountMinSketch to parquet statistics
Open
Component: Java
Component: Parquet
Priority: Minor
Type: enhancement
- Dominant language
- Java
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- 3d 12h
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Description
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).
**Reporter**: [Alex Levenson](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=alexlevenson) / @isnotinvain
**Note**: *This issue was originally created as [PARQUET-42](https://issues.apache.org/jira/browse/PARQUET-42). Please see the [migration documentation](https://issues.apache.org/jira/browse/PARQUET-2502) for further details.*
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