Allow For Expressing Nullability of "Returns null only if all arguments evaluate to null"

substrait-io / substrait

A cross platform way to express data transformation, relational algebra, standardized record expression and plans.

https://substrait.io

Apache License 2.0

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Open vbarua opened 6 months ago

vbarua commented 6 months ago

The nullability of functions like coalesce, least_skip_null and greatest_skip_null can be expressed in words as:

The function returns null only if all arguments evaluate to null.

or equivalently

The function returns non-null if any of the inputs are non-null.

There is currently no mechanism for explaining this nullability.