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Posted to dev@pig.apache.org by "Michael Howard (JIRA)" <ji...@apache.org> on 2018/01/17 19:22:01 UTC
[jira] [Updated] (PIG-5328) expressionOperator
Divide.equalsZero(DataType.BIGDECIMAL) is invalid
[ https://issues.apache.org/jira/browse/PIG-5328?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Michael Howard updated PIG-5328:
--------------------------------
Environment: pig source HEAD as of Jan 2017 ... probably goes all the way back to initial implementation of BigDecimal support (was: pig source HEAD as of Jan 2017 ... prob goes all the way back to initial implementation of BigDecimal support)
> expressionOperator Divide.equalsZero(DataType.BIGDECIMAL) is invalid
> --------------------------------------------------------------------
>
> Key: PIG-5328
> URL: https://issues.apache.org/jira/browse/PIG-5328
> Project: Pig
> Issue Type: Bug
> Components: impl
> Affects Versions: 0.16.0, 0.17.0
> Environment: pig source HEAD as of Jan 2017 ... probably goes all the way back to initial implementation of BigDecimal support
> Reporter: Michael Howard
> Priority: Major
> Original Estimate: 0.25h
> Remaining Estimate: 0.25h
>
> Divide.equalsZero(DataType.BIGDECIMAL) is flawed in that it uses an invalid test for == ZERO in the case of BigDecimal.
>
> ./physicalLayer/expressionOperators/Divide.java tests the divisor for zero in order to avoid DivideByZero.
> The test is performed using a method equalsZero(...)
> Divide.equalsZero() is given 'protected' access, but I could not find other references ... should be 'private'
> equalsZero() implementation dispatches on dataType to type-specific predicates ... the BigDecimal implementation is incorrect
> The method BigDecimal.equals(other) is intended to be used for object equality, not numerical equality. (Their justification is that equals() is used in hash-table lookups in java Collections.) BigDecimal numbers are not normalized and scale is an important attribute. Scale is included in BigDecimal.equals(). The values "0" and "0.00" have different scales and are not considered "equals()"
> Comparisons for numeric equality need to be done using compareTo()
> In the special case of comparing to zero, BigDecimal.signum() is the best.
> The current code is
> {{ case DataType.BIGDECIMAL:}}
> {{ return BigDecimal.ZERO.equals((BigDecimal) a);}}
> needs to be changed to
> {{ case DataType.BIGDECIMAL:}}
> {{ return ((BigDecimal) a).signum() == 0;}}
>
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