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From "Prashant Prakash (JIRA)" <j...@apache.org>
Subject [jira] [Created] (KYLIN-1304) Incorrect count estimate upon HyperLogLogPlusCounter.merge operation.
Date Tue, 12 Jan 2016 03:34:39 GMT
Prashant Prakash created KYLIN-1304:
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             Summary: Incorrect count estimate upon HyperLogLogPlusCounter.merge operation.
                 Key: KYLIN-1304
                 URL: https://issues.apache.org/jira/browse/KYLIN-1304
             Project: Kylin
          Issue Type: Bug
    Affects Versions: v1.1.1
            Reporter: Prashant Prakash


We are using hllc12 for evaluating uniques for a measure in a table partitioned over date.
The uniques estimate for individual dates 2016-01-07, 2016-01-08, 2016-01-09 are 93,728,324,
90,982,364, 45,485,278 respectively. 
But the uniques across days, which is calculated through HyperLogLogPlusCounter.merge operation
gives a incorrect value 67,980,576. 




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