influxdata/influxdb · error

Expected timestamp data type

Error message

Expected timestamp data type

What it means

A panic in the same test mock ScalarUDF's `invoke_with_args` in date_bin_wallclock.rs. After confirming three arguments, it destructures the source argument's DataType; if it is not DataType::Timestamp (with a timezone), it panics with "Expected timestamp data type". It validates that the UDF under test receives timestamp-typed source and origin arguments.

Solutions

1. Ensure the test's source/origin expressions are explicitly typed as Timestamp(_, Some(tz)) (use ScalarValue::TimestampNanosecond with a timezone or .cast_to).
2. Verify the mock's return_type/coercion signatures still force timestamp inputs.
3. Print source.data_type() at the panic to identify the unexpected type.

Example fix

// before
let DataType::Timestamp(_, tz) = source.data_type() else {
    panic!("Expected timestamp data type");
};
// after
let DataType::Timestamp(_, tz) = source.data_type() else {
    panic!("expected timestamp data type, got {:?}", source.data_type());
};

assert!(matches!(source.data_type(), DataType::Timestamp(_, Some(_))), "source must be a timestamp with tz, got {:?}", source.data_type());

fn as_timestamp_tz(dt: &DataType) -> Option<&Option<Arc<str>>> {
    match dt { DataType::Timestamp(_, tz) => Some(tz), _ => None }
}

let DataType::Timestamp(_, tz) = source.data_type() else {
    panic!("expected timestamp data type, got {:?}", source.data_type());
};

When it happens

Trigger: The mock UDF is invoked where source.data_type() is not a Timestamp — e.g. the test passes Int64 or Null-typed literals, or return_type/type-coercion changes propagate a different type.

Common situations: Happens after changing test literals without casting to TimestampNanosecond, or after DataFusion coercion changes that no longer force timestamp types before invocation.

Understand the failure class

Background: Type mismatch errors: IllegalArgumentException, TypeError and type guards across 150 open-source libraries — this error's family across 150 libraries.

Related errors

• Expected three arguments
• Error computing AND
• Expected array value
• expected bucket id, got string
• expected bucket id, got TS range

AI-assisted analysis of influxdata/influxdb@06200ef96b (2026-09-19). Data as JSON: /api/errors/c8b4aba7d53f04f8. Report an issue: GitHub.

Appendix: source

Thrown at core/query_functions/src/date_bin_wallclock.rs:931

        fn name(&self) -> &'static str {
            "test_date_bin_udf"
        }

        fn signature(&self) -> &Signature {
            &self.signature
        }

        fn return_type(&self, arg_types: &[DataType]) -> Result<DataType> {
            Ok(arg_types[1].clone())
        }

        fn invoke_with_args(&self, args: ScalarFunctionArgs) -> Result<ColumnarValue> {
            let [_, source, origin] = args.args.as_slice() else {
                panic!("Expected three arguments");
            };
            assert_eq!(source.data_type(), origin.data_type());
            let DataType::Timestamp(_, tz) = source.data_type() else {
                panic!("Expected timestamp data type");
            };
            assert!(tz.is_some());
            Ok(source.clone())
        }
    }

    fn arg_to_fields(args: &[ColumnarValue]) -> Vec<FieldRef> {
        args.iter()
            .enumerate()
            .map(|(idx, val)| Arc::new(Field::new(format!("arg_{idx}"), val.data_type(), false)))
            .collect()
    }

    fn return_field(dt: DataType) -> FieldRef {
        Arc::new(Field::new("r", dt, false))
    }
}

View on GitHub (pinned to 06200ef96b)