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https://issues.apache.org/jira/browse/FLINK-10014?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16565027#comment-16565027
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Xingcan Cui commented on FLINK-10014:
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Copied from another JIRA.
[~xccui]: Personally, I prefer the former solution because it's much easier
(especially for functions take multiple numeric params). Besides, for a great
number of functions, we could not directly calculate on BigDecimal (e.g., to
calculate log, we should first get the double value from a BigDecimal and
that's equivalent to a pre-cast). The drawback of this solution may be the
wrong return type. The later solution looks like a more formal one.
[~twalthr]: We should first investigate if we can let Calcite convert simple
literals to double. Explicit casts are not a nice solution but at least they
make the operation explicit. If we would automatically cast the type to double
we would lose precision which might be unintended. A corresponding BigDecimal
method would also return a BigDecimal and would cause high serialization
overhead for Flink applications even though a simple double would do the job.
> Fix the decimal literal parameter problem for arithmetic functions in Table
> ---------------------------------------------------------------------------
>
> Key: FLINK-10014
> URL: https://issues.apache.org/jira/browse/FLINK-10014
> Project: Flink
> Issue Type: Improvement
> Components: Table API & SQL
> Reporter: Xingcan Cui
> Priority: Major
>
> Most of the arithmetic functions added in Flink only consider double type
> parameters (e.g., def log(base: Double, x: Double): Double =...). However, by
> Calcite, the decimal literals are automatically cast to BigDecimal, which
> cannot be directly applied (e.g., LOG(3.0, 9.0) throws an unsupported call
> exception). Explicit type cast can make these functions accessible but seems
> not an elegant solution.
> We could consider automatically casting the BigDecimal type to Double or
> adding the corresponding methods for BigDecimal type.
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