.. _ksql_operations: KSQL Operations =============== Watch the `screencast of Taking KSQL to Production `_ on YouTube. ================================================ Local Development and Testing with Confluent CLI ================================================ For development and testing purposes, you can use Confluent CLI to spin up services on a single host. For more information, see the :ref:`quickstart`. .. include:: ../../includes/cli.rst :start-after: cli_limitations_start :end-before: cli_limitations_end =============================== Installing and Configuring KSQL =============================== You have a number of options when you set up KSQL Server. For more information on installing and configuring KSQL, see the following topics. - :ref:`install_ksql` - :ref:`ksql-server-config` - :ref:`ksql-param-reference` =================================== Starting and Stopping KSQL Clusters =================================== KSQL provides start and stop scripts. ksql-server-start This script starts the KSQL server. It requires a server configuration file as an argument and is located in the ``/bin`` directory of your |cp| installation. For more information, see :ref:`start_ksql-server`. ksql-server-stop This script stops the KSQL server. It is located in the ``/bin`` directory of your |cp| installation. ============= Health Checks ============= - The KSQL REST API supports a "server info" request at ``http://:8088/info`` and a basic server health check endpoint at ``http://:8088/healthcheck``. - Check runtime stats for the KSQL server that you are connected to via ``DESCRIBE EXTENDED `` and ``EXPLAIN ``. - Run ``ksql-print-metrics`` on a KSQL server. For example, see this `blog post `_. .. _ksql-monitoring-and-metrics: ====================== Monitoring and Metrics ====================== KSQL includes JMX (Java Management Extensions) metrics which give insights into what is happening inside your KSQL servers. These metrics include the number of messages, the total throughput, throughput distribution, error rate, and more. .. include:: includes/ksql-includes.rst :start-after: enable_JMX_metrics_start :end-before: enable_JMX_metrics_end The ``ksql-print-metrics`` command line utility collects these metrics and prints them to the console. You can invoke this utility from your terminal: .. code:: bash $ /bin/ksql-print-metrics Your output should resemble: .. code:: bash 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 :ref:`streams_monitoring`. ================= Capacity Planning ================= The :ref:`Capacity Planning guide ` describes how to size your KSQL clusters. =============== Troubleshooting =============== ------------------------------------ SELECT query hangs and doesn’t stop? ------------------------------------ Queries in KSQL, including non-persistent queries such as ``SELECT * FROM myTable EMIT CHANGES``, are continuous streaming queries. Streaming queries will not stop unless explicitly terminated. To terminate a non-persistent query in the KSQL CLI you must type ``Ctrl + C``. -------------------------------------------------- No results from ``SELECT * FROM`` table or stream? -------------------------------------------------- This is typically caused by the query being configured to process only newly arriving data instead, and no new input records are being received. To fix, do one of the following: - Run this command: ``SET 'auto.offset.reset' = 'earliest';``. For more information, see :ref:`install_cli-config` and :ref:`ksql-server-config`. - Write new records to the input topics. ------------------------------------------------------------ Can’t create a stream from the output of windowed aggregate? ------------------------------------------------------------ KSQL doesn't support structured keys, so you can't create a stream from a windowed aggregate. ------------------------------------------ KSQL doesn’t clean up its internal topics? ------------------------------------------ Make sure that your |ak-tm| cluster is configured with ``delete.topic.enable=true``. For more information, see :cp-javadoc:`deleteTopics|clients/javadocs/org/apache/kafka/clients/admin/AdminClient.html`. ---------------------------------------- KSQL CLI doesn’t connect to KSQL server? ---------------------------------------- The following warning may occur when you start the KSQL CLI. .. code:: bash **************** WARNING ****************** Remote server address may not be valid: Error issuing GET to KSQL server Caused by: java.net.SocketException: Connection reset Caused by: Connection reset ******************************************* Also, you may see a similar error when you create a KSQL query by using the CLI. .. code:: bash Error issuing POST to KSQL server Caused by: java.net.SocketException: Connection reset Caused by: Connection reset In both cases, the CLI can't connect to the KSQL server, which may be caused by one of the following conditions. - KSQL CLI isn't connected to the correct KSQL server port. - KSQL server isn't running. - KSQL server is running but listening on a different port. Check the port that KSQL CLI is using ------------------------------------- Ensure that the KSQL CLI is configured with the correct KSQL server port. By default, the server listens on port ``8088``. For more info, see :ref:`Starting the KSQL CLI `. Check the KSQL server configuration ----------------------------------- In the KSQL server configuration file, check that the list of listeners has the host address and port configured correctly. Look for the ``listeners`` setting: .. code:: bash listeners=http://0.0.0.0:8088 Or if you are running over IPv6: :: listeners=http://[::]:8088 For more info, see :ref:`Starting KSQL Server `. Check for a port conflict ------------------------- There may be another process running on the port that the KSQL server listens on. Use the following command to check the process that's running on the port assigned to the KSQL server. This example checks the default port, which is ``8088``. .. code:: bash netstat -anv | egrep -w .*8088.*LISTEN Your output should resemble: .. code:: bash tcp4 0 0 *.8088 *.* LISTEN 131072 131072 46314 0 In this example, ``46314`` is the PID of the process that's listening on port ``8088``. Run the following command to get info on the process. .. code:: bash ps -wwwp Your output should resemble: .. code:: bash io.confluent.ksql.rest.server.KsqlServerMain ./config/ksql-server.properties If the ``KsqlServerMain`` process isn't shown, a different process has taken the port that ``KsqlServerMain`` would normally use. Check the assigned listeners in the KSQL server configuration, and restart the KSQL CLI with the correct port. ------------------------------------------------ Replicated topic with Avro schema causes errors? ------------------------------------------------ Confluent Replicator renames topics during replication, and if there are associated Avro schemas, they aren't automatically matched with the renamed topics. In the KSQL CLI, the ``PRINT`` statement for a replicated topic works, which shows that the Avro schema ID exists in |sr|, and KSQL can deserialize the Avro message. But ``CREATE STREAM`` fails with a deserialization error: .. code:: bash CREATE STREAM pageviews_original (viewtime bigint, userid varchar, pageid varchar) WITH (kafka_topic='pageviews.replica', value_format='AVRO'); [2018-06-21 19:12:08,135] WARN task [1_6] Skipping record due to deserialization error. topic=[pageviews.replica] partition=[6] offset=[1663] (org.apache.kafka.streams.processor.internals.RecordDeserializer:86) org.apache.kafka.connect.errors.DataException: pageviews.replica at io.confluent.connect.avro.AvroConverter.toConnectData(AvroConverter.java:97) at io.confluent.ksql.serde.connect.KsqlConnectDeserializer.deserialize(KsqlConnectDeserializer.java:48) at io.confluent.ksql.serde.connect.KsqlConnectDeserializer.deserialize(KsqlConnectDeserializer.java:27) The solution is to register schemas manually against the replicated subject name for the topic: .. code:: bash # Original topic name = pageviews # Replicated topic name = pageviews.replica curl -X POST -H "Content-Type: application/vnd.schemaregistry.v1+json" --data "{\"schema\": $(curl -s http://localhost:8081/subjects/pageviews-value/versions/latest | jq '.schema')}" http://localhost:8081/subjects/pageviews.replica-value/versions ---------------------- Check KSQL server logs ---------------------- If you're still having trouble, check the KSQL server logs for errors. .. code:: bash confluent log ksql-server Look for logs in the default directory at ``/usr/local/logs`` or in the ``LOG_DIR`` that you assign when you start the KSQL CLI. For more info, see :ref:`Starting the KSQL CLI `.