[
https://issues.apache.org/jira/browse/PIG-5328?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Michael Howard updated PIG-5328:
--------------------------------
Release Note: the division operator checks for a zero denominator to
prevent a divide-by-zero exception. Unlike other numeric types, BigDecimal has
multiple representations of zero with different scales ... 0, 0.0, 0.00, etc.
Previous versions of pig were were not properly detecting zero values with
non-zero scales when performing denominator check prior to division.
Status: Patch Available (was: Open)
TestDivide unit test updated
BigDecimal.signum() == 0 now used to test for values numerically equal to zero.
> 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: 0.17.0, 0.16.0
> Environment: pig source HEAD as of Jan 2018 ... probably goes all the
> way back to initial implementation of BigDecimal support
> Reporter: Michael Howard
> Assignee: 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;}}
>
--
This message was sent by Atlassian JIRA
(v7.6.3#76005)
