KTable-KTable Foreign-Key Join Semantics

Question

The documentation from Confluent website mentions the following:

The left KTable can have multiple records which map to the same key on the right KTable. An update to a single left KTable entry may result in a single output event, provided the corresponding key exists in the right KTable. Consequently, a single update to a right KTable entry will result in an update for each record in the left KTable that has the same foreign key.

Looking at the example below the explanation:

According to explanation, in the case of inner join (10, baz) on the right side should trigger two records on the left side that will be added to resulting join table. But in the explanation it's not in the table. Is this a typo? Or I'm missing something.

Answer 1

Yes, it's an error in the docs. -- Thanks for calling it out. We will fix it.

Btw: feel free to email to [email protected] if you encounter errors in the docs so we can fix them!