The timestamp is always stored -- it's a metadata field that was added to the message format in 0.10.0.
By default, Producer uses System.currentTimeMillis() to set the timestamp before it send the record to the broker. Or you can explicitly set the timestamp by yourself. The default TimestampExtractor returns this metadata timestamp for each record. This gives you event-time processing semantics. Thus, you usually don't need to worry about this -- it's happens all out-of-box. Furthermore in Streams, the timestamp will be set explicitly using "stream time" (thus, Streams preserves event-time semantics). "stream time" is an internally tracked timestamp, that aligns to the progress during processing. I omit the details for now, but basically "stream time" aligns with the record metadata timestamp of the currently processed record. -Matthias On 5/4/17 12:02 PM, Murad Mamedov wrote: > Hi, > > In Producer record, we have timestamp. > - Where it is actually stored, if stored? > - When producing resorts with KStream.to() which timestamp is used, if used? > > In order to guarantee proper timestamp, do we have to always implement > timestamp extractor? > > Thanks in advance. >
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