Spark Structured Streaming：在翻滚窗口结束时输出结果，而不是批次

Question

我希望火花流的输出在翻转窗口的末端发送到水槽，而不是在批处理间隔。

我从一个Kafka流读取并输出到另一个Kafka流。

查询和写入输出的代码如下：

Dataset<Row> sqlResult = session.sql("select window, user, sum(amount) as amount from users where type = 'A' group by window(timestamp, '1 minute', '1 minute'), user");
sqlResult = sqlResult.select(to_json(struct("window", "user", "amount")).as("value"));

StreamingQuery query = sqlResult.writeStream()
    .format("kafka")
    .option("kafka.bootstrap.servers", "localhost:9092")
    .option("topic", "aggregated-topic")
    .option("checkpointLocation", "c:/tmp")
    .outputMode(OutputMode.Update())
    .start();

当我在一分钟的窗口内为一个特定用户发送多个记录时，我希望在一分钟结束时这些事件的总数。

但我在输出Kafka流上获得了多个输出，并在其中写入了间歇聚合。

如。

我将在一分钟内发送以下7条记录，但间隔一定时间。

json prettyprint-override">
>{ "id" : 123, "type": "A", "user": "tukaram", "amount": 10}
>{ "id" : 123, "type": "A", "user": "tukaram", "amount": 10}
>{ "id" : 123, "type": "A", "user": "tukaram", "amount": 10}
>{ "id" : 123, "type": "A", "user": "tukaram", "amount": 10}
>{ "id" : 123, "type": "A", "user": "tukaram", "amount": 10}
>{ "id" : 123, "type": "A", "user": "tukaram", "amount": 10}
>{ "id" : 123, "type": "A", "user": "tukaram", "amount": 10}

我得到的结果是：

{"window":{"start":"2020-09-18T14:35:00.000+05:30","end":"2020-09-18T14:36:00.000+05:30"},"user":"tukaram","amount":10.0}
{"window":{"start":"2020-09-18T14:35:00.000+05:30","end":"2020-09-18T14:36:00.000+05:30"},"user":"tukaram","amount":20.0}
{"window":{"start":"2020-09-18T14:35:00.000+05:30","end":"2020-09-18T14:36:00.000+05:30"},"user":"tukaram","amount":40.0}
{"window":{"start":"2020-09-18T14:35:00.000+05:30","end":"2020-09-18T14:36:00.000+05:30"},"user":"tukaram","amount":60.0}
{"window":{"start":"2020-09-18T14:35:00.000+05:30","end":"2020-09-18T14:36:00.000+05:30"},"user":"tukaram","amount":70.0}

可以看到，输出在同一个窗口中，但有多个输出。

我想要的是一分钟结束时的单个输出

{"window":{"start":"2020-09-18T14:35:00.000+05:30","end":"2020-09-18T14:36:00.000+05:30"},"user":"tukaram","amount":70.0}

我该如何实现呢？

Answer 1

将流写入接收器时，需要设置处理触发器。

你用。具有适当触发器值的DataStreamWriter的触发器（trigger.ProcessingTime）。

StreamingQuery query = sqlResult.writeStream()
        .trigger(Trigger.ProcessingTime("1 minute")) //this