fml2 created KAFKA-12328:
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Summary: Find out partition of a store iterator
Key: KAFKA-12328
URL: https://issues.apache.org/jira/browse/KAFKA-12328
Project: Kafka
Issue Type: Wish
Reporter: fml2
This question was posted [on
stakoverflow|https://stackoverflow.com/questions/66032099/kafka-streams-how-to-get-the-partition-an-iterartor-is-iterating-over]
and got an answer but the solution is quite complicated hence this ticket.
In my Kafka Streams application, I have a task that sets up a scheduled (by the
wall time) punctuator. The punctuator iterates over the entries of a store and
does something with them. Like this:
{code:java}
var store = context().getStateStore("MyStore");
var iter = store.all();
while (iter.hasNext()) {
var entry = iter.next();
// ... do something with the entry
}
// Print a summary (now): N entries processed
// Print a summary (wish): N entries processed in partition P
{code}
Is it possible to find out which partition the punctuator operates on? The java
docs for {{ProcessorContext.partition()}} states that this method returns
{{-1}} within punctuators.
I've read [Kafka Streams: Punctuate vs
Process|https://stackoverflow.com/questions/50776987/kafka-streams-punctuate-vs-process]
and the answers there. I can understand that a task is, in general, not tied
to a particular partition. But an iterator should be tied IMO.
How can I find out the partition?
Or is my assumption that a particular instance of a store iterator is tied to a
partion wrong?
What I need it for: I'd like to include the partition number in some log
messages. For now, I have several nearly identical log messages stating that
the punctuator does this and that. In order to make those messages "unique" I'd
like to include the partition number into them.
Since I'm working with a single store here (which might be partitioned), I
assume that every single execution of the punctuator is bound to a single
partition of that store.
It would be cool if there were a method {{iterator.partition}} (or similar) to
get this information.
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