Error: unsupported C API type: 27 (UUID)

[arouel]

When working with the DuckLake extension, and appending data to a table with a UUID column I get the error: unsupported C API type: 27.

Ideally, the error message would tell a user the type name. Besides that, it would be great to support appending to UUID columns as well.

package test;

import static org.assertj.core.api.BDDAssertions.*;

import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.UUID;

import org.duckdb.DuckDBConnection;
import org.junit.jupiter.api.Test;

class DuckLakeAppenderTest {

    @Test
    void uuid_fails_with_new_appender_ducklake() throws SQLException {
        try (
            var connection = (DuckDBConnection) DriverManager.getConnection("jdbc:duckdb:");
            var statement = connection.createStatement()
        ) {
            statement.execute("""
                ATTACH 'ducklake:/tmp/test_uuid.ducklake' AS my_ducklake;
                USE my_ducklake;
                CREATE TABLE IF NOT EXISTS test (id UUID);
                """);

            var uuid = UUID.randomUUID().toString();
            try (var appender = connection.createAppender("main", "test")) {
                appender.beginRow();
                appender.append(uuid);
                appender.endRow();
                // java.sql.SQLException: Appender error, catalog: 'null', schema: 'main', table: 'test', message: unsupported C API type: 27
            }

            try (var rs = statement.executeQuery("select * from test")) {
                rs.next();
                then(rs.getString(1)).isEqualTo(uuid);
            }
        }
    }
}

[staticlibs]

@arouel

the error message would tell a user the type name

The problem is that the type name may be not known on Java side, when in future the standalone shared lib of DuckDB is used over C API. So the number - the actual value of the C API type enum - is used instead.

it would be great to support appending to UUID columns as well.

Yes, UUID can be added, just it must be passed as UUID object or a number - passing and parsing a String does not look appropriate for the Appender.

[arouel]

the error message would tell a user the type name

The problem is that the type name may be not known on Java side, when in future the standalone shared lib of DuckDB is used over C API. So the number - the actual value of the C API type enum - is used instead.

Maybe we can point with a link or message to the enum?

When you say "in future the standalone shared lib of DuckDB is used over C API": Would this enable a native image built with GraalVM?

it would be great to support appending to UUID columns as well.

Yes, UUID can be added, just it must be passed as UUID object or a number - passing and parsing a String does not look appropriate for the Appender.

I would prefer having both option (UUID object or numbers). When you say passed as a number, how do you imagine it? Two long values like long mostSigBits, long leastSigBits?

[staticlibs]

Maybe we can point with a link or message to the enum?

Yes, sounds like a good idea, will look into it.

Two long values like long mostSigBits, long leastSigBits?

Yes, something like this. To provide a way (may be not the most convenient) to allow appending UUIDs without requiring to instantiate UUID object per element. The similar way like it is done for HUGEINT, which can be appended as a BigInteger or as two long's.