feat: Implement Spark-compatible CAST float/double to string - Githubissues

apache / datafusion-comet

Apache DataFusion Comet Spark Accelerator

https://datafusion.apache.org/comet

Apache License 2.0

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feat: Implement Spark-compatible CAST float/double to string #346

Closed mattharder91 closed 2 weeks ago

mattharder91 commented 2 weeks ago

Which issue does this PR close?

Closes #312

Rationale for this change

Improve compatibility with Apache Spark

What changes are included in this PR?

Add custom implementation of CAST from float to string rather than delegate to DataFusion
Adapted test function to opt out the ansi mode exception testing as there is never a casting exception thrown between rusts(float,double) to string

How are these changes tested?

added unit tests for float
added unit tests for double

Further Considerations

A potential problem could be there for denormalized precision values.

Scalas Double.MinPositiveValue is 4.9E-324 the denormalized value and parses correctly to 4.9E-324 while rust outputs 5E-324.