apache/seatunnel · error · IllegalArgumentException

Unsupported Date unit:

Error message

Unsupported Date unit: 

What it means

DateTypeWriter.writeToVector writes to DateDayVector or DateMilliVector depending on the Arrow DateType unit. Arrow only defines DAY and MILLISECOND units, so this guard fires only if an unknown/future DateUnit appears, and throws IllegalArgumentException. It means the field's Arrow date unit is not one the writer knows how to handle.

Source

Thrown at seatunnel-connectors-v2/connector-lance/src/main/java/org/apache/seatunnel/connectors/seatunnel/lance/sink/writers/DateTypeWriter.java:49

/** Writer for Date type. */
public class DateTypeWriter extends BaseTypeWriter {
    @Override
    public void writeToVector(
            FieldVector vector,
            ArrowType arrowType,
            Object value,
            int rowIndex,
            BufferAllocator allocator) {
        ArrowType.Date dateType = (ArrowType.Date) arrowType;
        if (dateType.getUnit() == DateUnit.DAY) {
            long epochDay = convertToEpochDay(value);
            ((DateDayVector) vector).setSafe(rowIndex, (int) epochDay);
        } else if (dateType.getUnit() == DateUnit.MILLISECOND) {
            long epochMilli = convertToEpochMilli(value);
            ((DateMilliVector) vector).setSafe(rowIndex, epochMilli);
        } else {
            throw new IllegalArgumentException("Unsupported Date unit: " + dateType.getUnit());
        }
    }

    private long convertToEpochDay(Object value) {
        if (value instanceof LocalDate) {
            return ((LocalDate) value).toEpochDay();
        } else if (value instanceof java.sql.Date) {
            return ((java.sql.Date) value).toLocalDate().toEpochDay();
        } else {
            return LocalDate.parse(value.toString()).toEpochDay();
        }
    }

    private long convertToEpochMilli(Object value) {
        if (value instanceof LocalDate) {
            return ((LocalDate) value)
                    .atStartOfDay(ZoneId.systemDefault())
                    .toInstant()

View on GitHub (pinned to cf67b549a7)

Solutions

1. Use standard Arrow DateUnits: DateUnit.DAY or DateUnit.MILLISECOND in the schema.
2. Upgrade the SeaTunnel lance connector (and its lance/arrow SDK) if a newer Arrow version introduced new units.
3. Pre-normalize date columns to DateUnit.DAY in any custom schema conversion code feeding this writer.

Example fix

// before
new ArrowType.Date(DateUnit.SECOND) // invalid unit
// after
new ArrowType.Date(DateUnit.MILLISECOND)

ArrowType t = field.getType(); if (t instanceof ArrowType.Date && ((ArrowType.Date) t).getUnit() != DateUnit.DAY && ((ArrowType.Date) t).getUnit() != DateUnit.MILLISECOND) throw new IllegalArgumentException("unsupported date unit");

try { writer.write(row); } catch (IllegalArgumentException e) { if (e.getMessage().startsWith("Unsupported Date unit")) { /* rebuild schema with DAY/MILLISECOND */ } throw e; }

When it happens

Trigger: writeToVector is called with an ArrowType.Date whose getUnit() is neither DAY nor MILLISECOND — practically only with a nonstandard/extended Arrow build or a manually constructed ArrowType with a bogus unit.

Common situations: Custom schema construction or a Lance/Arrow version introducing a new DateUnit that this connector version does not know; hand-built Arrow schemas in tests using an invalid unit.

Related errors

• Unsupported date value type:
• TABLE_DATASET_WRITE_ST_ROW_EXCEPTION
• Unsupported timestamp value type:
• Unsupported FloatingPoint precision:
• Unsupported Int bit width:

AI-assisted analysis of apache/seatunnel@cf67b549a7 (2026-09-10). Data as JSON: /api/errors/39ecf5d566322de7. Report an issue: GitHub.