How to Query Stream from Beginning in ksqlDB

To process the source stream from the beginning:

SET 'auto.offset.reset' = 'earliest';

You only need to set this property once in each session.

Note that you can set this session property as a ksqlDB cluster configuration to apply to any ksqlDB session opened for that cluster.

By default, stream queries return the records produced after you submit the query. This is the default configuration for the Apache Kafka Consumer that is used internally by ksqlDB when using the Kafka Streams API.