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https://issues.apache.org/jira/browse/HIVE-25653?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17462512#comment-17462512
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Ashish Sharma edited comment on HIVE-25653 at 12/20/21, 11:28 AM:
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[~zabetak]
I have corrected the column data from int to decimal in the example.
*Code Snippet*
public class MyClass {
public static void main(String args[]) {
System.out.println(10230.72+10230.72+10230.72);
}
}
*Output* -
30692.159999999996
*Expected* -
30692.16
Because of the double and floating point arithmetic accuracy issue in java
language. Output of UDFs and UDAFs like STDDEV are getting affected hence we
are getting output (*0.0000000000005940794514955821*) instead of (*0.0*)
But since other engine like MYSQL, POSTGRES are returning the similar value. So
we can ignore arithmetic accuracy issue in UDFs for now.
I have created a revert request - https://github.com/apache/hive/pull/2897
was (Author: ashish-kumar-sharma):
[~zabetak]
*Code Snippet*
public class MyClass {
public static void main(String args[]) {
System.out.println(10230.72+10230.72+10230.72);
}
}
*Output* -
30692.159999999996
*Expected* -
30692.16
Because of the double and floating point arithmetic accurcy issue in java
language. Output of UDFs and UDAFs like STDDEV are getting affected hence we
are getting output (*0.0000000000005940794514955821*) instead of (*0.0*)
But since other engine like MYSQL are returning the same value. So we can
ignore arithmetic accuracy issue in UDFs for now.
I have created a revert request - https://github.com/apache/hive/pull/2897
> Incorrect results returned by STDDEV, STDDEV_SAMP, STDDEV_POP for floating
> point data types.
> --------------------------------------------------------------------------------------------
>
> Key: HIVE-25653
> URL: https://issues.apache.org/jira/browse/HIVE-25653
> Project: Hive
> Issue Type: Improvement
> Components: UDF
> Affects Versions: 3.1.0, 3.1.2
> Reporter: Ashish Sharma
> Assignee: Ashish Sharma
> Priority: Major
> Labels: pull-request-available
> Fix For: 4.0.0
>
> Time Spent: 1h 20m
> Remaining Estimate: 0h
>
> Description
> *Script*-
> create table test ( col1 decimal );
> insert into 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 from test;
> *Result*-
> STDDDEV_SAMP STDDEV
> STDDEV_POP
> 5.940794514955821E-13 5.42317860890711E-13 5.42317860890711E-13
> *Expected*-
> STDDDEV_SAMP STDDEV
> STDDEV_POP
> 0 0
> 0
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