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https://issues.apache.org/jira/browse/HIVE-17724?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16195490#comment-16195490
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Yuzhou Sun commented on HIVE-17724:
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+1 think it's a limitation of the type
According to
https://cwiki.apache.org/confluence/display/Hive/LanguageManual+Types and
https://en.wikipedia.org/wiki/Single-precision_floating-point_format , FLOAT is
4-byte single precision floating point number, which uses 8 bits for the
exponent
Transfer the numbers to binary number:
1507284611 -> 1011001110101110101011010000011
1507284608 -> 1011001110101110101011010000000
> Cast from string to float gives strange result
> ----------------------------------------------
>
> Key: HIVE-17724
> URL: https://issues.apache.org/jira/browse/HIVE-17724
> Project: Hive
> Issue Type: Bug
> Affects Versions: 1.1.0
> Environment: Hive 1.1.0-cdh5.10.0
> Subversion
> file:///data0/jenkins/workspace/generic-package-ubuntu64-14-04/CDH5.10.0-Packaging-Hive-2017-01-20_11-52-43/hive-1.1.0+cdh5.10.0+859-1.cdh5.10.0.p0.71~trusty
> -r Unknown
> Reporter: David Scarlatti
>
> this query:"select CAST ('1507284611' as int), CAST ('1507284611' as bigint),
> CAST ('1507284611' as float), CAST ('1507284611' as double), CAST
> ('1507284611' as decimal)"
> returns
> 1507284611 1507284611 1507284608 1507284611 1507284611
> cast as float is the only one changing the numeric value.
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