Flink SQL Client中的Chained (Event) Time Windows

Flink SQL Cookbook中有Chained (Event) Time Windows

该md文件举了两个例子，

前面一个例子是Chained Windows

后面一个例子是Non-Chained Windows

 

该md文件的前半部分图示如下:

上图中存在两个server_logs_window_5m

①Chained Windows

②Non-Chained Windows

所以②比①更加有计算上的效率，但是耦合性也更强。

 

上图图示中，三条红线就是所谓的Chained (Event) Time Windows

这个概念出自Ververcica公司的flink sql cookbook

Chained (Event) Time Windows的SQL距离

 

Chained (Event) Time Windows的SQL举例(对应上图中的3个红色箭头):

Chained (Event) Time Windows的数据流向	具体对应的SQL
server_logs_window_1m->server_logs_window_5m	CREATE TEMPORARY VIEW server_logs_window_5m AS  SELECT    TUMBLE_START(window_end, INTERVAL '5' MINUTE) AS window_start,   TUMBLE_ROWTIME(window_end, INTERVAL '5' MINUTE) AS window_end,   SUM(total_size) AS total_size,   SUM(num_requests) AS num_requests FROM server_logs_window_1m GROUP BY    TUMBLE(window_end, INTERVAL '5' MINUTE);
server_logs_window_1m->avg_request_size_1m	INSERT INTO avg_request_size_1m SELECT   window_start,   window_end,    total_size/num_requests AS avg_size FROM server_logs_window_1m;
server_logs_window_5m->avg_request_size_5m	INSERT INTO avg_request_size_5m SELECT   window_start,   window_end,    total_size/num_requests AS avg_size FROM server_logs_window_5m;

 

 

Chained Windows与Non-Chained Windows的SQL写法对比

Windows类型	具体对应的SQL
Chained Windows	CREATE TEMPORARY VIEW server_logs_window_5m AS  SELECT    TUMBLE_START(window_end, INTERVAL '5' MINUTE) AS window_start,   TUMBLE_ROWTIME(window_end, INTERVAL '5' MINUTE) AS window_end,   SUM(total_size) AS total_size,   SUM(num_requests) AS num_requests FROM server_logs_window_1m GROUP BY    TUMBLE(window_end, INTERVAL '5' MINUTE);
Non-Chained Windows	CREATE TEMPORARY VIEW server_logs_window_5m AS  SELECT    TUMBLE_START  (log_time, INTERVAL '5' MINUTE) AS window_start,   TUMBLE_ROWTIME(log_time, INTERVAL '5' MINUTE) AS window_end,   SUM(size) AS total_size,   COUNT(*) AS num_requests FROM server_logs GROUP BY    TUMBLE(log_time, INTERVAL '5' MINUTE);

 

 

 

 

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