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Swapna Kasula commented on PHOENIX-3390: ---------------------------------------- The function APPROX_SUM is very similar to the existing aggregate function we have is 'SUM(X)', to allow in the select statements. However we pass col to the SUM(X), APPROX_SUM works the same way as : select APPROX_SUM(col) from table; This is how I visualize: Example: rowkey col1 col2 google hll1 hll2 yahoo hll3 hll4 msn hll5 hll6 select APPROX_SUM(col1) from table; //returns union of (hll1 U hll3 U hll5) for all rows select APPROX_SUM(col1) from table where rowkey ='google' or rowkey ='yahoo' // this returns unions of (hll1 U hll3) > Custom UDAF for HyperLogLogPlus > ------------------------------- > > Key: PHOENIX-3390 > URL: https://issues.apache.org/jira/browse/PHOENIX-3390 > Project: Phoenix > Issue Type: New Feature > Reporter: Swapna Kasula > Priority: Minor > > With ref # PHOENIX-2069 > Custome UDAF to aggregate/union of Hyperloglog's of a column and returns a > Hyperloglog. > select hllUnion(col1) from table; //returns a Hyperloglog, which is the > union of all hyperloglog's from all rows for column 'col1' -- This message was sent by Atlassian JIRA (v6.3.4#6332)