Hi! Any idea why:

SELECT sign(CAST(0 AS INTEGER))

or

SELECT sign(CAST(0 AS BIGINT))

works, but

SELECT sign(CAST(0 AS TINYINT))

and

SELECT sign(CAST(0 AS SMALLINT))

error out? More specifically, using PyFlink (Python 3.10.12, PyFlink 1.17.1):

st_env.sql_query("SELECT sign(CAST(0 AS TINYINT))").to_pandas()

Error below:

I think it's already mentioned in the stacktrace:

Assignment conversion not possible from type "float" to type "byte"

The default conversion class for

TINYINT

is

Byte

, and for

SMALLINT

is

Short

Sorry, I don't think I understand. Is this expected behavior, then? If I want to safely use

SIGN

with numeric types, do I need to always manually upcast to

INTEGER

or larger first?

Is this expected behavior, then?

Under the hood, the

SIGN

function calls

java.lang.Math#signum

,

java.lang.Integer#signum

or

java.lang.Long#signum

, according to input type, respectively. While for input type

byte

or

short

, it'll be first cast to

int

and then passed to

java.lang.Integer#signum

. While the result type

int

cannot be safely cast back to

byte

or

short

, the exception is thrown.

do I need to always manually upcast to INTEGER or larger first?

I believe so.

Thanks for the explanation!