feat: add decimal argument support to round function #713
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The round function has a number of variants to support different numeric types. This commit adds support for rounding decimals. This is required for the spark module. Signed-off-by: Andrew Coleman <[email protected]>
andrew-coleman
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jacques-n,
cpcloud,
westonpace,
EpsilonPrime and
vbarua
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| and this value cannot be exactly represented, this specifies how | ||
| to round it. | ||
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| - TIE_TO_EVEN: round to nearest value; if exactly halfway, tie |
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Can this happen with decimal representations? I'd argue all of the floating point handling stuff here does not apply.
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Why would these not apply? For example, the input value 2.5 could be represented exactly in a decimal type, but rounding it to the nearest integer would result in 2 if the rounding mode is TIE_TO_EVEN or 3 if the mode is TIE_AWAY_FROM_ZERO.
| @@ -268,3 +268,43 @@ scalar_functions: | |||
| AWAY_FROM_ZERO, TIE_DOWN, TIE_UP, TIE_TOWARDS_ZERO, TIE_TO_ODD ] | |||
| nullability: DECLARED_OUTPUT | |||
| return: fp64? | |||
| - args: | |||
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For all other decimal functionality we have placed them in _decimal.yaml files. Not sure if we want to have just this one function in a file by itself though.
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| When `s` is a negative number, the rounding is | ||
| performed to the left side of the decimal point | ||
| as specified by `s`. |
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Does this operation affect the scale? We should probably clarify that here.
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I guess this function could return a different decimal type (i.e. reduce the precision and the scale parameters), but I was working on the assumption that it would just return a different value. I'm not sure if that is what you are asking.
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Let's not assume. Let's add some expected behaviors here. Once we get tests inside core, we can transplant those into test cases. And if this is the behaviors of spark we're trying to match, we shouldn't probably just put this in a spark function file (or name it spark_round here). Decimal behavior is often quite different between different systems.
The round function has a number of variants to support different numeric types. This commit adds support for rounding decimals. This is required for the spark module.