René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"QAPage","mainEntity":{"@type":"Question","name":"订阅的触发时机是什么？","text":"
我现在正在测试订阅相关的内容，使用了文档里的示例代码。现在测试的效果是：
\n当插入第一条数据时（创建Timeseries）会在控制台打印插入的数据。
\n当重新启动时会打印全部的数据（没设置起止时间）
\n但是在执行过程中并没有打印新插入的数据。
\n
    private void pollConsumer (String topic, String host, Integer port) {\n        final Properties config = new Properties();\n        config.put(ConsumerConstant.CONSUMER_ID_KEY, \"c2\");\n        config.put(ConsumerConstant.CONSUMER_GROUP_ID_KEY, \"cg1\");\n\n        final SubscriptionPullConsumer consumer1 = new SubscriptionPullConsumer(config);\n\n        consumer1.open();\n        consumer1.subscribe(topic);\n\n//        Set<String> set = new HashSet<>();\n//        set.add(topic);\n\n        for (int i = 0;i < 100;i++) {\n            LockSupport.parkNanos(500);\n            final List<SubscriptionMessage> messages = consumer1.poll(1000);\n            for (final SubscriptionMessage message : messages) {\n                for (final SubscriptionSessionDataSet dataSet : message.getSessionDataSetsHandler()) {\n                    System.out.println(dataSet.getColumnNames());\n                    System.out.println(dataSet.getColumnTypes());\n                    while (dataSet.hasNext()) {\n                        System.out.println(dataSet.next());\n                        Tablet tablet = dataSet.getTablet();\n                    }\n                }\n            }\n        }\n\n        consumer1.unsubscribe(topic);\n        consumer1.close();\n    }\n
\n
控制台打印
\n
2041 [main] INFO  o.a.i.s.s.c.SubscriptionPullConsumer - SubscriptionPullConsumer SubscriptionPullConsumer{subscribedTopicNames=[topic01], consumerGroupId=cg1, isClosed=false, consumerId=c2, fileSaveDir=E:\\test\\TestUDF\\iotdb-subscription, autoCommit=true} poll empty message from topics [topic01] after 1000 millisecond(s) \n[Time, root.sky.a.temperature]\n[INT64, DOUBLE]\n1735868811188\t-1.0\n1735868817134\t-2.0\n[Time, root.sky.a.temperature]\n[INT64, DOUBLE]\n1735869028109\t-2.0\n1735869030243\t-2.0\n3291 [main] INFO  o.a.i.s.s.c.SubscriptionPullConsumer - SubscriptionPullConsumer SubscriptionPullConsumer{subscribedTopicNames=[topic01], consumerGroupId=cg1, isClosed=false, consumerId=c2, fileSaveDir=E:\\test\\TestUDF\\iotdb-subscription, autoCommit=true} poll empty message from topics [topic01] after 1000 millisecond(s) \n4140 [main] INFO  o.a.i.s.s.c.SubscriptionPullConsumer - SubscriptionPullConsumer SubscriptionPullConsumer{subscribedTopicNames=[topic01], consumerGroupId=cg1, isClosed=false, consumerId=c2, fileSaveDir=E:\\test\\TestUDF\\iotdb-subscription, autoCommit=true} poll empty message from topics [topic01] after 1000 millisecond(s) \n...\n
\n
在循环的过程中仅会在创建 timeseries 时打印新增的数据。
","upvoteCount":1,"answerCount":1,"acceptedAnswer":{"@type":"Answer","text":"
新增的数据在 flush 后会触发订阅，可以在命令行中手动执行 flush 命令观察是否打印了新插入的数据
","upvoteCount":3,"url":"https://github.com/apache/iotdb/discussions/14620#discussioncomment-11722436"}}}