Operations Index

KSQL versus ksqlDB

Overview of key differences between KSQL and ksqlDB.

Install and configure ksqlDB

You have a number of options when you set up ksqlDB Server. For more information on installing and configuring ksqlDB, see the following topics.

Health Checks

  • The ksqlDB REST API supports a "server info" request at http://<server>:8088/info and a basic server health check endpoint at http://<server>:8088/healthcheck.
  • Check runtime stats for the ksqlDB server that you are connected to via DESCRIBE EXTENDED <stream or table> and EXPLAIN <name of query>.
  • Run ksql-print-metrics on a ksqlDB server. For example, see this blog post.

For more information, see Check the health of a ksqlDB Server.

Capacity Planning

The Capacity Planning guide describes how to size your ksqlDB clusters.


If ksqlDB isn't behaving as expected, see Troubleshoot ksqlDB issues

Monitoring and Metrics

ksqlDB includes JMX (Java Management Extensions) metrics which give insights into what is happening inside your ksqlDB servers. These metrics include the number of messages, the total throughput, throughput distribution, error rate, and more.

To enable JMX metrics, set JMX_PORT before starting the ksqlDB server:

export JMX_PORT=1099 && \
<path-to-confluent>/bin/ksql-server-start <path-to-confluent>/etc/ksqldb/ksql-server.properties

The ksql-print-metrics command line utility collects these metrics and prints them to the console. You can invoke this utility from your terminal:


Your output should resemble:

messages-consumed-avg: 96416.96196183885
messages-consumed-min: 88900.3329377909
error-rate: 0.0
num-persistent-queries: 2.0
messages-consumed-per-sec: 193024.78294586178
messages-produced-per-sec: 193025.4730374501
num-active-queries: 2.0
num-idle-queries: 0.0
messages-consumed-max: 103397.81191436431

For more information about Kafka Streams metrics, see Monitoring Streams Applications.

Next Steps

Last update: 2020-03-19