public void appendStringFormVal(String val) {
            SQLType type = columnTypes[curColIndex];
            switch (type) {
                case INT:
                    appendInt(Strings.isEmpty(val) ? 0 : Integer.parseInt(val));
                    break;
                case BIGINT:
                    appendLong(Strings.isEmpty(val) ? 0 : Long.parseLong(val));
                    break;
                case FLOAT:
                    appendFloat(Strings.isEmpty(val) ? 0 : Float.parseFloat(val));
                    break;
                case DOUBLE:
                    appendDouble(Strings.isEmpty(val) ? 0 : Double.parseDouble(val));
                    break;
                case VARCHAR:
                    appendString(Strings.isEmpty(val) ? "" : val);
                    break;
                case DATE:
                    appendLong(Strings.isEmpty(val) ? 0 : DateTimeUtil.parseDate(UTF8Util.toUtf8(val)));
                    break;
                case TIME:
                    appendInt(Strings.isEmpty(val) ? 0 : DateTimeUtil.parseTime(UTF8Util.toUtf8(val)));
                    break;
                case DATETIME:
                    appendLong(Strings.isEmpty(val) ? 0 : DateTimeUtil.parseDateTime(UTF8Util.toUtf8(val)));
                    break;
                default:
                    throw new IllegalStateException();
            }
        }
A simple row can only store simple values like int, double, string. But cannot store multi-value column.
indexr-segment/src/main/java/io/indexr/segment/helper/SimpleRow.java