A materialized view stores a continuously updated, precomputed representation of query results. In ksqlDB, it is locally stored in RocksDB and replicated through Kafka, allowing keyed queries to return current state immediately without scanning a topic. section 8.4.1
This contrasts with querying a stream or table directly: a pull query scans the underlying Kafka topic or changelog for the latest matching record, while a materialized view reads an already indexed result. Pull queries remain transient and terminate after returning the current state. section 8.4.1
Aggregated order state
An order-count view groups orders by country and maintains the resulting totals as events arrive, making current aggregate state available for immediate keyed reads. section 8.4.1
Listing 8.5 Counting the number of orders per country
CREATE TABLE Orders_Count_By_Country AS
SELECT country, COUNT(*) AS total_orders #1
FROM Orders
GROUP BY country #2
EMIT CHANGES;
Browse a ksqlDB definition that creates a maintained table of order counts grouped by country. section 8.4.1
