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https://issues.apache.org/jira/browse/DERBY-5546?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13171116#comment-13171116
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Dag H. Wanvik commented on DERBY-5546:
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In SQLReal, the method setBigDecimal has this line:
setValue(bigDecimal.floatValue());
The method BigDecimal.floatValue has this caveat in the Javadoc:
" Note that even when the return value is finite, this conversion can lose
information about the precision of the BigDecimal value. "
So, if the actual value is Double.MIN_VALUE, the value here is set to 0.0
without any error.
In contrast, when we try to update a DOUBLE column, the method used is
setValue(bigDecimal.doubleValue())
This will not underflow, but subsequently gets caught by the range check in
NumberDataType#normalizeDouble() where the value is checked against
Limits.DB2_SMALLEST_DOUBLE.
However, if the value represented in the BigDecimal is even smaller than
Double.MIN_VALUE, the call "bigDecimal.doubleValue()" would yield 0.0 and we
would have the same behavior for DOUBLE, too.
> ResultSet#updateBigDecimal on a REAL column does not do underflow checking
> --------------------------------------------------------------------------
>
> Key: DERBY-5546
> URL: https://issues.apache.org/jira/browse/DERBY-5546
> Project: Derby
> Issue Type: Bug
> Components: JDBC
> Affects Versions: 10.8.2.2
> Reporter: Dag H. Wanvik
> Priority: Minor
> Attachments: MissingUnderflowCheck.java
>
>
> In contrast, ResultSet#updateBigDecimal on a FLOAT or DOUBLE column gives the
> expected error on underflow. Cf. the attached repro program
> MissingUnderflowCheck.
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