[multistage] Type Inference for Case/When Has Some Issues

[ankitsultana]

Detected this in #10409

There's a todo left in FunctionOperand as well related to this: https://github.com/apache/pinot/blob/master/pinot-query-runtime/src/main/java/org/apache/pinot/query/runtime/operator/operands/FunctionOperand.java#L53

Essentially after the PR linked above, for the query below a couple of project nodes are merged and the case/when starts returning a Double at runtime which is compared against 16.0 which is a float.

SELECT intCol, CASE WHEN (SELECT SUM(floatCol) FROM {tbl1}) > 16.0 THEN 'Large sum' ELSE 'Small sum' END AS aggVal, strCol FROM {tbl1}

cc: @walterddr

[abhioncbr]

Please assign this ticket to me.

[abhioncbr]

@walterddr just pushed the initial commit; I want to validate my approach and understanding. Can you please have a look?

[walterddr]

@ankitsultana could you share some query examples that have failed? so we can add test cases for this.

[ankitsultana]

Only case I had detected was present in the UTs. I think the PR already removes the "ignored" flag.

[walterddr]

thank you will comment on the PR for some additional test examples