Interval fields returned as `String`

[raszi]

Description

DuckDB supports interval types, but the DuckDB JDBC Driver returns these fields as String. In comparison the PostgreSQL JDBC Driver returns a custom org.postgresql.util.PGInterval instance.

Expectation

This makes the integrations for the DuckDB JDBC Driver problematic in certain situations. I would expect a custom class to be returned similar to the org.duckdb.user.DuckDBUserArray, org.duckdb.user.DuckDBMap, or org.duckdb.user.DuckDBUserStruct classes.

Even if this new class behaves the same as a String instance, using a different class would make it possible for the implementations to convert that to a proper Duration type at the end, or whatever the end-user prefers.

Repro case

https://github.com/raszi/duckdb-interval-testcase

[staticlibs]

Hi, thanks for the report! Yes, I agree this should be implemented in a similar way to ARRAY and STRUCT.

[raszi]

I've just noticed that setting a duration value as a parameter is not possible either.