What causes " : I don't know how to convert a bignumber to binary." in pentaho/pentaho-kettle?

Convert the BigDecimal to a string via getString() and call getBinary on a TYPE_STRING meta.

pentaho/pentaho-kettle · error · KettleValueException

: I don't know how to convert a bignumber to binary.

Error message

 : I don't know how to convert a bignumber to binary.

What it means

ValueMetaBase.getBinary() has no conversion from TYPE_BIGNUMBER (BigDecimal) to binary bytes and throws KettleValueException. Only string-typed values support byte conversion in this class; arbitrary-precision numbers must be converted to strings first.

Solutions

Convert the BigDecimal to a string via getString() and call getBinary on a TYPE_STRING meta.
Change the field metadata to TYPE_STRING before binary output.
Use getString() with a decimal format mask instead.
Catch KettleValueException and handle bignumber fields explicitly.

Example fix

// before
ValueMetaInterface vm = new ValueMeta("bn", ValueMetaInterface.TYPE_BIGNUMBER);
byte[] b = vm.getBinary(bigDecimalValue); // throws
// after
String s = vm.getString(bigDecimalValue);
ValueMetaInterface vmStr = new ValueMeta("bn", ValueMetaInterface.TYPE_STRING);
byte[] b = vmStr.getBinary(s);

Defensive patterns

Strategy: type-guard

Validate before calling

if (meta.getType() == ValueMetaInterface.TYPE_BIGNUMBER) { throw new IllegalArgumentException("Field " + meta.getName() + " is a bignumber; convert to String before getBinary()"); }

Type guard

boolean isBinaryReadable(ValueMetaInterface vm) { return vm.getType() == ValueMetaInterface.TYPE_STRING || vm.getType() == ValueMetaInterface.TYPE_BINARY; }

Try / catch

try { byte[] b = vm.getBinary(value); } catch (KettleValueException e) { byte[] b = vm.getString(value).getBytes(StandardCharsets.UTF_8); }

Prevention

Convert BigDecimal fields to strings before byte output.
Gate getBinary() on the declared value type.
Use format masks via getString() for decimal formatting.
Audit generic serializers to reject unsupported types up front.

When it happens

Trigger: Calling getBinary(object) on a value meta whose type is ValueMetaInterface.TYPE_BIGNUMBER.

Common situations: Binary output of decimal/precision-critical fields; generic serialization code iterating row fields; output plugins expecting bytes for every type.

Understand the failure class

Background: "is not a compatible type" / "cannot merge" errors: when a value's type doesn't match what the library requires — this error's family across 65 libraries.

Related errors

AI-assisted analysis of pentaho/pentaho-kettle@f3058517a1 (2026-09-13). Data as JSON: /api/errors/77e3721e9a268231. Report an issue: GitHub.

Appendix: source

Thrown at core/src/main/java/org/pentaho/di/core/row/value/ValueMetaBase.java:2407

      case TYPE_DATE:
        throw new KettleValueException( toString() + " : I don't know how to convert a date to binary." );
      case TYPE_STRING:
        switch ( storageType ) {
          case STORAGE_TYPE_NORMAL:
            return convertStringToBinaryString( (String) object );
          case STORAGE_TYPE_BINARY_STRING:
            return (byte[]) object;
          case STORAGE_TYPE_INDEXED:
            return convertStringToBinaryString( (String) index[( (Integer) object ).intValue()] );
          default:
            throw new KettleValueException( toString() + " : Unknown storage type " + storageType + " specified." );
        }
      case TYPE_NUMBER:
        throw new KettleValueException( toString() + " : I don't know how to convert a number to binary." );
      case TYPE_INTEGER:
        throw new KettleValueException( toString() + " : I don't know how to convert an integer to binary." );
      case TYPE_BIGNUMBER:
        throw new KettleValueException( toString() + " : I don't know how to convert a bignumber to binary." );
      case TYPE_BOOLEAN:
        throw new KettleValueException( toString() + " : I don't know how to convert a boolean to binary." );
      case TYPE_SERIALIZABLE:
        throw new KettleValueException( toString() + " : I don't know how to convert a serializable to binary." );

      default:
        throw new KettleValueException( toString() + " : Unknown type " + type + " specified." );
    }
  }

  @Override
  public byte[] getBinaryString( Object object ) throws KettleValueException {
    // If the input is a binary string, we should return the exact same binary
    // object IF
    // and only IF the formatting options for the storage metadata and this
    // object are the same.
    //
    if ( isStorageBinaryString() && identicalFormat ) {

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