如何从KSQL窗口表对应的kafka主题中获取窗口开始或结束时间？

Question

I want to get window start timestamp (here is 1530008520000) from kafka-console-consumer command.

It works with KSQL:

ksql> select * from DEV_MONITOR_RULE_2557_104782_233_2_TABLE;

1530008581051 | 2557 : Window{start=1530008520000 end=-} | 2557 | 2 | 1530008581051

But it does not work with kafka-console-consumer?

./bin/kafka-console-consumer --zookeeper 10.12.0.157:2181 --topic DEV_MONITOR_RULE_2557_104782_233_2_TABLE

{"HITCOUNTS":2,"TENANTID":2557,"HITTIME":1530008581051}

How to print window start time (here is 1530008520000) from kafka-console-consumer?

Thanks!

Answer 1

The window start time is reflected in the ROWTIME of the KSQL message, and in the timestamp of the Kafka message. This timestamp you can access using the standard APIs for working with Kafka messages.

AFAIK the kafka-console-consumer doesn't support showing timestamp. However something like kafkacat does.

Here's some aggregated data in KSQL, with the ROWTIME showing the start of the window (and TIMESTAMPTOSTRING being used to pretty-print it):

ksql> SELECT TIMESTAMPTOSTRING(ROWTIME, 'yyyy-MM-dd HH:mm:ss'), ROWTIME, STARS, STAR_COUNT FROM RATINGS_AGG2;
2018-06-27 09:30:00 | 1530091800000 | 1 | 2
2018-06-27 09:30:00 | 1530091800000 | 4 | 6
2018-06-27 09:30:00 | 1530091800000 | 2 | 2
2018-06-27 09:30:00 | 1530091800000 | 3 | 3

Now the same topic in kafkacat :

$ kafkacat -b localhost:9092 -C -K: \
  -f '\nTimestamp: %T\t\tValue (%S bytes): %s' \
  -t RATINGS_AGG2

Timestamp: 1530091800000                Value (26 bytes): {"STAR_COUNT":1,"STARS":1}
Timestamp: 1530091800000                Value (26 bytes): {"STAR_COUNT":2,"STARS":1}
Timestamp: 1530091800000                Value (26 bytes): {"STAR_COUNT":3,"STARS":3}
Timestamp: 1530091800000                Value (26 bytes): {"STAR_COUNT":5,"STARS":1}
Timestamp: 1530091800000                Value (26 bytes): {"STAR_COUNT":6,"STARS":3}
Timestamp: 1530091800000                Value (26 bytes): {"STAR_COUNT":7,"STARS":1}
Timestamp: 1530091800000                Value (26 bytes): {"STAR_COUNT":7,"STARS":3}
Timestamp: 1530091800000                Value (26 bytes): {"STAR_COUNT":9,"STARS":1}
Timestamp: 1530091800000                Value (26 bytes): {"STAR_COUNT":9,"STARS":3}

Answer 2

您是否尝试过 kafka-console-consumer 选项print.timestamp=true ？

$ kafka-console-consumer --property print.timestamp=true ...