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From Jonathan Roy <jonathan....@caldera.com.INVALID>
Subject Questions about state stores and KSQL
Date Wed, 11 Jul 2018 08:41:58 GMT
Hi Kafka users,

I am very new to Kafka and more globally to stream processing, and am trying to understand
some of the concepts used by Kafka. From what I understand, a key-value state store is created
on each processor node that performs stateful operations such as aggregations or joins. Let’s
take an example. I have an ‘orders’ stream and a ‘users’ table, and I want to enrich
the orders events with the corresponding users information, using the KSQL CLI:

CREATE STREAM orders_enriched AS SELECT o.id <http://o.id/>, o.article, o.quantity,
o.userId, u.name, u.address, u.email FROM orders o LEFT JOIN users u ON o.userId = u.id <http://u.id/>;

Where is located the state store in this case? What will it contain exactly? Is it possible
to query it from another node?

Thanks beforehand for your help!

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