For KStream-to-KTable joins, what are the output type, windowing, co-partitioning, and join type?

• A. Output: KStream; Windowed; Yes; Key Or Foreign-Key Based
• B. Output: KTable; Non-windowed; Yes; Key Or Foreign-Key Based
• C. Output: KStream; Windowed; No; Key Based
• D. Output: KStream; Non-windowed; Yes; Key Based

Answer: (D)

KStream-to-KTable joins produce a stream of joined records, not a table, because you’re taking each incoming record from the stream and enriching it with the latest value from the table. That means the output type is a KStream.

Windowing isn’t used for this kind of join. The join uses the current key to fetch the corresponding value from the KTable, so there’s no time windowing applied to group or limit results.

Co-partitioning is required to efficiently perform the join. Both sides must be partitioned by the same key, so records with the same key land on the same partition and can be joined without an extra repartition step.

The join is keyed, meaning the join condition is based on the record key (not some foreign key or a separate join key). The KStream uses its key to look up the KTable’s value and produce the joined result.

So the correct characterization is: output is a KStream, non-windowed, co-partitioning is required (Yes), and the join is Key Based.