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:
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
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.
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 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.
