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Posted to gitbox@hive.apache.org by GitBox <gi...@apache.org> on 2021/11/05 04:48:18 UTC
[GitHub] [hive] ashish-kumar-sharma commented on a change in pull request #2760: HIVE-25653: Precision problem in STD, STDDDEV_SAMP,STDDEV_POP
ashish-kumar-sharma commented on a change in pull request #2760:
URL: https://github.com/apache/hive/pull/2760#discussion_r743388404
##########
File path: ql/src/test/queries/clientpositive/sdtdev.q
##########
@@ -0,0 +1,12 @@
+create table test ( col1 decimal(10,3) );
+insert into test values (10230.72),(10230.72),(10230.72),(10230.72),(10230.72),(10230.72),(10230.72);
+select STDDEV_SAMP(col1) AS STDDEV_6M , STDDEV(col1) as STDDEV ,STDDEV_POP(col1) as STDDEV_POP , variance(col1) as variance,var_pop(col1) as var_pop,var_samp(col1) as var_samp from test;
+
+create table testpoint ( col1 decimal(10,3));
+insert into testpoint values (0.12345678),(0.25362123),(0.62437485),(0.65133746),(0.98765432),(0.12435647),(0.7654321445);
+select STDDEV_SAMP(col1) AS STDDEV_6M , STDDEV(col1) as STDDEV ,STDDEV_POP(col1) as STDDEV_POP , variance(col1) as variance,var_pop(col1) as var_pop,var_samp(col1) as var_samp from testpoint;
+
+create table testint(col1 int);
+insert into testint values (85),(86),(100),(76),(81),(93),(84),(99),(71),(69),(93),(85),(81),(87),(89);
+select STDDEV_SAMP(col1) AS STDDEV_6M , STDDEV(col1) as STDDEV ,STDDEV_POP(col1) as STDDEV_POP, variance(col1) as variance,var_pop(col1) as var_pop,var_samp(col1) as var_samp from testint;
+
Review comment:
Done
##########
File path: ql/src/java/org/apache/hadoop/hive/ql/udf/generic/GenericUDAFStd.java
##########
@@ -90,7 +92,9 @@ public GenericUDAFEvaluator getEvaluator(TypeInfo[] parameters)
* use it, etc.
*/
public static double calculateStdResult(double variance, long count) {
- return Math.sqrt(variance / count);
+ BigDecimal bvariance = new BigDecimal(variance);
+ BigDecimal result = bvariance.divide(new BigDecimal(count));
+ return Math.sqrt(result.doubleValue());
Review comment:
Done
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