ResultSetMetaData.isSigned() incorrectly returns false for HUGEINT columns

[zhicwu]

Since version 1.2.2.0, ResultSetMetaData.isSigned() method correctly returns true for standard signed integer types including TINYINT, SMALLINT, INTEGER, and BIGINT.

However, it has been observed that for columns with the HUGEINT data type, isSigned() incorrectly returns false.

According to the documentation, HUGEINT is a signed sixteen-byte integer type. Therefore, ResultSetMetaData.isSigned() should return true for HUGEINT columns to accurately reflect its signed nature.

[staticlibs]

@zhicwu

Hi, thanks for the report! I wonder if you have an example of this and can check the column type that is returned from ResultSetMetaData (perhaps you are getting UHUGEINT returned instead)?

With trivial examples like SELECT 42::HUGEINT I am getting true from ResultSetMetaData#isSigned() (on both v1.2.2.0 and the latest dev).

[zhicwu]

Hi @staticlibs, thank you for your response. You are right; the DuckDB JDBC driver does return true for isSigned() for a HUGEINT column. The problem in my program was that it incorrectly set this value to false because the mapped JDBC data type was JAVA_OBJECT. Is there a reason it's not mapped to NUMERIC or DECIMAL?

[staticlibs]

@zhicwu

Yes, I agree that JAVA_OBJECT is a bad choice for a fallback type, as it is supposed to have the following meaning in JDBC:

The type JAVA_OBJECT is used by a database whose type system has been extended so that it can store Java objects directly.

Though I don't think NUMERIC or DECIMAL can be used for HUGEINT, as they have well-defined meaning in SQL for rational fixed-point numbers.

Instead I've changed the fallback type (that is also applied for HUGEINT) to OTHER in #209.