liyang owns the HLL code, I have assigned the JIRA to him On Wed, Jan 13, 2016 at 12:27 PM, vipul jhawar <vipul.jha...@gmail.com> wrote:
> Hi Luke > > Please check this issue once and let us know if merging HLL for uniques has > been stable for you guys as we recently saw a huge discrepancy and wanted > to check with you guys if we should totally avoid this option for now or we > can bank upon it. > > Thanks > > On Tue, Jan 12, 2016 at 9:04 AM, Prashant Prakash (JIRA) <j...@apache.org> > wrote: > > > Prashant Prakash created KYLIN-1304: > > --------------------------------------- > > > > 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. > > > > > > > > > > -- > > This message was sent by Atlassian JIRA > > (v6.3.4#6332) > > > -- Regards, *Bin Mahone | 马洪宾* Apache Kylin: http://kylin.io Github: https://github.com/binmahone
