Apache Kafka Quick Start Guide

Writing to a topic

So far, we have processed the data and printed the results in real time. To send these results to another topic, we use a CREATE command modality, where it is specified from a SELECT.

Let's start by writing the uptime as a string and writing the data in a comma-delimited format, shown as follows (remember that KSQL supports comma-delimited, JSON, and Avro formats). At the moment, it's enough because we're only writing one value:

ksql> CREATE STREAM uptimes WITH (kafka_topic='uptimes', value_format='delimited') AS SELECT CAST((STRINGTOTIMESTAMP('2017-11-18','yyyy-MM-dd''T''HH:mm:ss.SSSZ')-STRINGTOTIMESTAMP(lastStartedAt,'yyyy-MM-dd'))/86400/1000 AS string) AS uptime FROM healthchecks;

The output is similar to this:

Message ...