Some basic questions. When an index is created, like for null values,what component decides that a given value corresponds to null value. For eg, for a float column, -infinity value is mapped to null. Same for NaN and +infinity.

Pinot used to require a config for default null value, which is like -inf. This is when pinot read value null, it will assign -inf as null. After the implementation of null support, Pinot will create a null bitmap to indicate the null values, which is the true null support.

So where do we keep this config?

by default pinot doesn’t support null, but you can follow this to enable it: https://docs.pinot.apache.org/developers/advanced/null-value-support