The timestamp has many different purposes. As mentioned already, it used to expired data via retention time. It's also used for stream processing via Streams API. All processing is based on those timestamps for windowing and joining of streams.
-Matthias On 1/18/18 7:57 PM, Stephen Powis wrote: > A common use case is for calculating a "processing lag time" comparing the > record's timestamp (when it was published/persisted) against the current > time that the consumer 'consumed' it. In theory, the delta is 'how far > behind' the consumer is, tho you can come up with a variety of reasons why > this wouldn't actually be true. > > On Fri, Jan 19, 2018 at 12:52 PM, 1095193...@qq.com <1095193...@qq.com> > wrote: > >> kafka does not delete message when message is consumed, it will purge >> message when this message is expired. I guess this timeStamp is for >> checking whether message is expired. >> >> >> >> 1095193...@qq.com >> >> From: Jake Yoon >> Date: 2018-01-19 11:46 >> To: users >> Subject: What's the use of timestamp in ProducerRecord? >> Hi, I am very new to Kafka. >> And I have a very basic question. >> >> Kafka doc says, >> >> *ProducerRecord >> <https://kafka.apache.org/0100/javadoc/org/apache/kafka/clients/producer/ >> ProducerRecord.html#ProducerRecord(java.lang.String,%20java.lang.Integer,% >> 20java.lang.Long,%20K,%20V)>* >> (String >> <http://docs.oracle.com/javase/7/docs/api/java/lang/ >> String.html?is-external=true> >> topic, Integer >> <http://docs.oracle.com/javase/7/docs/api/java/lang/ >> Integer.html?is-external=true> >> partition, Long >> <http://docs.oracle.com/javase/7/docs/api/java/lang/ >> Long.html?is-external=true> >> timestamp, K >> <https://kafka.apache.org/0100/javadoc/org/apache/kafka/clients/producer/ >> ProducerRecord.html> >> key, V >> <https://kafka.apache.org/0100/javadoc/org/apache/kafka/clients/producer/ >> ProducerRecord.html> >> value) >> >> and I know the default timestamp is the current time. But I am not sure >> what's the use of it. >> >> - Is it just to log when the record is added? >> - How Kafka use it for? >> - Are there any other uses of it? >> - Can "Consumer" retrieves the timestamp of the "ProducerRecord"? >> >> Thanks, >> >
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