MySQL Flink Watermark实现事件时间处理的关键技术

#1.创建表
CREATE TABLE source_table ( 
 user_id STRING, 
 price BIGINT,
 `timestamp` bigint,
 row_time AS TO_TIMESTAMP(FROM_UNIXTIME(`timestamp`)),
 watermark for row_time as row_time - interval '0' second
) WITH (
  'connector' = 'socket',
  'hostname' = 'node1', 
  'port' = '9999',
  'format' = 'csv'
);
#2.数据查询SQL
select 
user_id,
count(*) as pv,
sum(price) as sum_price,
UNIX_TIMESTAMP(CAST(tumble_start(row_time, interval '5' second) AS STRING)) * 1000  as window_start,
UNIX_TIMESTAMP(CAST(tumble_end(row_time, interval '5' second) AS STRING)) * 1000  as window_end
from source_table
group by
    user_id,
    tumble(row_time, interval '5' second);

#1.创建表
CREATE TABLE source_table ( 
 user_id STRING, 
 price BIGINT,
 `timestamp` bigint,
 row_time AS TO_TIMESTAMP(FROM_UNIXTIME(`timestamp`)),
 watermark for row_time as row_time - interval '2' second
) WITH (
  'connector' = 'socket',
  'hostname' = 'node1', 
  'port' = '9999',
  'format' = 'csv'
);
#2.Watermark的解释
WATERMARK FOR ts AS ts - INTERVAL '2' SECOND
这里的2，表示，数据允许延迟2秒钟到达，窗口会在(正常结束+延迟时间)后触发计算
#3.查询SQL
select 
user_id,
count(*) as pv,
sum(price) as sum_price,
UNIX_TIMESTAMP(CAST(tumble_start(row_time, interval '5' second) AS STRING)) * 1000  as window_start,
UNIX_TIMESTAMP(CAST(tumble_end(row_time, interval '5' second) AS STRING)) * 1000  as window_end
from source_table
group by
    user_id,
    tumble(row_time, interval '5' second);