...
Discussion thread: here
JIRA: here [Change the link from KAFKA-1 to your own ticket]15299
Please keep the discussion on the mailing list rather than commenting on the wiki (wiki discussions get unwieldy fast).
...
So if we create KStream from the stream of business events and create a KTable(s) from all database tables that store business entity data (for example using Change Data Capture) we can assemble complete Business Entity using stream-table joins . and then aggregating on event key.
For the Order Completion example above the sequence of order extraction from Kafka topics is as follows:
- As the first step Business event stream could be joined with business entity parent table using stream-table join on PK. Using the order management example on the diagram below this will be Order Processing Events stream joined with Orders KTable on OrderId key resulting in a stream of completed orders.
- As the second step the stream of completed orders could be left joined with Order Details table using the foreign key (OrderId) resulting in a stream of competed orders with corresponding order details.
...
- If order to order details relation 1:n then additional aggregation on OrderId will be required.
This KIP proposes the new Kafka Streams feature with capability to join the KStream with KTable using left Foreign Key Join
...