Peter Ebert created IMPALA-8759:
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Summary: Use double precision for HLL
Key: IMPALA-8759
URL: https://issues.apache.org/jira/browse/IMPALA-8759
Project: IMPALA
Issue Type: Improvement
Reporter: Peter Ebert
For /be/src/exprs/aggregate-functions-ir.cc the finalize function uses a float
which is only capable of 6-9 digits of precision. More accurate estimates for
larger cardinalities (beyond 999,999) should be possible with double precision.
Another c++ implementation uses double as well
[https://github.com/dialtr/libcount]
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