Apache Druid

```Select NVL(t1.__time, t2.__time) from 
select __time from table1) as t1
FULL OUTER JOIN
select __time from table2) as t2```

The above is an example query.
Though I used NVL function I am not able to replace the null values of t1.__time with values from t2.__time.

Hi Phani, is it possible that you have `useDefaultValuesForNulls` set to true?

Otherwise I've used coalesce() on full outer joins and have not seen a problem.  So also maybe try coalesce() to see if it behaves differently than nvl().

hey John, thanks for the reply.
Its the same with coalesce() as well.
Is `useDefaultValuesForNulls`  by default set to `true` ??

Prior to Druid 27 I believe it is defaulted to TRUE ... and maybe Druid 27 as well  ...  in Druid 28 it is for sure defaulted to FALSE

From the docs, a way to check:
> If a value cannot be cast to the target type, as in `CAST('foo' AS BIGINT)`, Druid a substitutes <https://druid.apache.org/docs/latest/querying/sql-data-types/#null-values|NULL>. When `druid.generic.useDefaultValueForNull = true` (legacy mode), Druid instead substitutes a default value, including when NULL values cast to non-nullable types.