When `drill.exec.functions.cast_empty_string_to_null` option is enabled
`to_date`, `to_time` and `to_timestamp` functions while converting string to according type in case if null or empty string values are passed will return NULL (to avoid CASE clauses which are littering a query and will work in accordance with their respective CAST counterparts) for both cases.
CASTs will be handled in a similar way (uniformly with numeric types):
|Value to cast||Now||Will be|
|'' (empty string)||Error in many cases (except numerical types)||NULL|
CAST empty string to null (in case of enabled option) will be supported by DATE, TIME, TIMESTAMP, INTERVAL YEAR, INTERVAL MONTH and INTERVAL DAY functions in addition to numeric types.