Null handing issue with Partial upserts and partialUpsertStrategies

[raghukn]

As described in the partial update behavior - https://docs.pinot.apache.org/basics/data-import/upsert

Below case is described:

With partial upsert, if the value is null in either the existing record or the new coming record, Pinot will ignore the upsert strategy and the null value:

(null, newValue) -> newValue

(oldValue, null) -> oldValue

(null, null) -> null

Partial Update is very desirable. But this behavior of ignoring fields present in payload but has null value, is not desirable. The fact that some one is sending null value show he / she intends to overwrite existing value. Other wise they would not have sent this column / value in the first place.

How do we get this behavior work correctly and incoming null not ignored?