code: private String partitionFilterToWhereClauseString(Expression expression) throws IOException
      {
          Expression.BinaryExpression be = (Expression.BinaryExpression) expression;
          OpType op = expression.getOpType();
          String opString = op.toString();
          switch (op)
          {
              case OP_EQ:
                  opString = " = ";
              case OP_GE:
              case OP_GT:
              case OP_LE:
              case OP_LT:
                  String name = be.getLhs().toString();
                  String value = be.getRhs().toString();
                  return String.format("%s %s %s", name, opString, value);
              case OP_AND:
                  return String.format("%s AND %s", partitionFilterToWhereClauseString(be.getLhs()), partitionFilterToWhereClauseString(be.getRhs()));
              default:
                  throw new IOException("Unsupported expression type: " + opString);
          }
      }
docs: Return cql where clauses for the corresponding partition filter. Make sure the data format matches
  Only support the following Pig data types: int, long, float, double, boolean and chararray