apache/seatunnel · error · SeaTunnelCsvFormatException

UNSUPPORTED_DATA_TYPE

UNSUPPORTED_DATA_TYPE

Error message

SeaTunnel array not support this data type [${sqlType}]

What it means

When converting a CSV array column, CsvDeserializationSchema maps each element to the declared SeaTunnel element type. If the element SqlType has no array-conversion branch (e.g. MAP, nested ARRAY, ROW), it throws SeaTunnelCsvFormatException with UNSUPPORTED_DATA_TYPE because element-wise conversion is only implemented for primitive types.

Source

Thrown at seatunnel-formats/seatunnel-format-csv/src/main/java/org/apache/seatunnel/format/csv/CsvDeserializationSchema.java:272

                        return objectArrayList.toArray(new Integer[0]);
                    case BIGINT:
                        return objectArrayList.toArray(new Long[0]);
                    case FLOAT:
                        return objectArrayList.toArray(new Float[0]);
                    case DOUBLE:
                        return objectArrayList.toArray(new Double[0]);
                    case DECIMAL:
                        return objectArrayList.toArray(new BigDecimal[0]);
                    case DATE:
                        return objectArrayList.toArray(new LocalDate[0]);
                    case TIME:
                        return objectArrayList.toArray(new LocalTime[0]);
                    case TIMESTAMP:
                        return objectArrayList.toArray(new LocalDateTime[0]);
                    case TIMESTAMP_TZ:
                        return objectArrayList.toArray(new OffsetDateTime[0]);
                    default:
                        throw new SeaTunnelCsvFormatException(
                                CommonErrorCode.UNSUPPORTED_DATA_TYPE,
                                String.format(
                                        "SeaTunnel array not support this data type [%s]",
                                        elementType.getSqlType()));
                }
            case MAP:
                SeaTunnelDataType<?> keyType = ((MapType<?, ?>) fieldType).getKeyType();
                SeaTunnelDataType<?> valueType = ((MapType<?, ?>) fieldType).getValueType();
                LinkedHashMap<Object, Object> objectMap = new LinkedHashMap<>();
                String[] kvs = field.split(separators[level + 1]);
                for (String kv : kvs) {
                    String[] splits = kv.split(separators[level + 2]);
                    if (splits.length < 2) {
                        objectMap.put(convert(splits[0], keyType, level + 1, fieldName), null);
                    } else {
                        objectMap.put(
                                convert(splits[0], keyType, level + 1, fieldName),
                                convert(splits[1], valueType, level + 1, fieldName));

View on GitHub (pinned to cf67b549a7)

Solutions

  1. Change the array element type in the schema to a supported primitive (INT, BIGINT, STRING, BOOLEAN, DOUBLE, DATE, TIME, TIMESTAMP).
  2. Flatten nested structures: encode MAP/ROW fields as JSON strings and parse downstream.
  3. Switch the source format to JSON/Parquet if nested types are genuinely required.

Example fix

// before
field = {name = "tags", type = "array<map<string,string>>"}
// after
field = {name = "tags", type = "array<string>"}
Defensive patterns

Strategy: validation

Validate before calling

Arrays.stream(rowType.getFieldTypes())
  .filter(t -> t instanceof ArrayType)
  .map(t -> ((ArrayType) t).getElementType().getSqlType())
  .forEach(t -> checkSupported(t)); // only primitives allowed

Try / catch

try { deserialize(record); } catch (SeaTunnelCsvFormatException e) { if (e.getCode() == UNSUPPORTED_DATA_TYPE) { /* fix schema or skip row */ } }

Prevention

When it happens

Trigger: Declaring a CSV column as array<MAP<...>>, array<array<...>>, or another non-primitive element type in the source schema; schema in config lists an element SqlType not in the supported set (INT, STRING, DATE, TIME, TIMESTAMP, etc.).

Common situations: Copy-pasting schema definitions from JSON/Parquet sources into a CSV source; trying to model nested data in flat CSV files.

Related errors

AI-assisted analysis of apache/seatunnel@cf67b549a7 (2026-09-10). Data as JSON: /api/errors/52775e56319818d2. Report an issue: GitHub.