@Override
    public long extractTimestamp(Row row) {

        try{
            Long extractTime = MathUtil.getLongVal(row.getField(pos));
            return getExtractTimestamp(extractTime);
        }catch (Exception e){
            logger.error("", e);
        }
        return lastTime;
    }
Custom watermark --- for eventtime
Date: 2017/12/28
Company: www.dtstack.com
@author xuchao
core/src/main/java/com/dtstack/flink/sql/watermarker/CustomerWaterMarkerForLong.java