ksqlDB in Confluent Control Center
Control Center provides the convenience of running streaming queries on one or more
ksqlDB clusters within its graphical user interface. The ksqlDB feature is
enabled by default in Control Center.
Important
If RBAC is enabled, the ability to view
and use ksqlDB in Control Center is determined by the assigned
roles and associated privileges configured in both ksqlDB and
Control Center.
For more information about ksqlDB, see ksqlDB Overview.
Tip
See the Confluent Platform Local or Docker
quick start guides for fast set ups of streams, tables, and persisted
running queries in Control Center.
ksqlDB applications page
To access the ksqlDB applications page, click the cluster from the navigation
bar and select ksqlDB from the cluster submenu.
Use the ksqlDB applications page to:
- View a summary of all ksqlDB applications connected to Control Center.
- Search for a ksqlDB application being managed by the Control Center instance.
- Browse topic messages.
- View the number of running queries, registered streams, and registered tables
for each ksqlDB application.
- Navigate to the ksqlDB Editor, Streams,
Tables, and Running Queries for each ksqlDB
application. Click the ksqlDB application name link to navigate to the ksqlDB
Editor and other pages.
ksqlDB Editor
To access the ksqlDB Editor page, click the ksqlDB application name in the
ksqlDB applications page.
Use the ksqlDB Editor page to create streams and tables, run SQL queries, and
browse messages.
After creating streams and tables, the resizeable streams and tables pane is
populated with the defined streams and tables for the application, beyond the
default KSQL_PROCESSING_LOG
:
- Streams are indicated with a blue St expandable node:
- Tables are indicated with a brown Tb expandable node:
Click a node to view the schema for a stream or table.
A Search box enables searching for streams and tables.
Download selected messages
Download selected rows of messages in a JSON format. You can download messages
from the Messages browser in Topics or
ksqlDB Editor.
Run a query in the ksqlDB Editor to activate the message browser area. After
the messages area is populated with messages, you can select messages for
download, whether the query is running or stopped.
Select one or more contiguous or non-contiguous rows. The Download button
becomes available and shows the number of selected messages.
Tip
Press the command key + click (Ctrl key on Windows) to select non-contiguous rows.
Press shift + click on a beginning and ending row to select
a contiguous range of messages.
Click the download button: . A file named selected_data_<n>.json
that contains the selected messages in JSON format is downloaded into your
downloads directory. The n represents the number of selected messages.
Example filename: selected_data_1.json
Example contents:
[{"VIEWTIME":1611859623088,"USERID":"User_3","PAGEID":"Page_93"}]
Streams
To access the Streams page, click the ksqlDB application name in the
ksqlDB applications page and click the Streams tab.
Use the Streams page to:
- View a summary of streams for the ksqlDB application.
- Search for streams.
- View the Describe stream output (analogous to the DESCRIBE
command in the ksqlDB CLI).
- Jump to the ksqlDB Editor page to query the stream.
- Drop a stream (analogous to the DROP STREAM
command in the ksqlDB CLI).
Click a stream to view its information, like the stream name, associated Kafka
topic, number of partitions and replicas, and the data format.
Tables
To access the Tables page, click the ksqlDB application name
in the ksqlDB applications page and click the Tables tab.
Use the Tables page to:
- View a summary of tables for the ksqlDB application.
- Search for tables.
- View the Describe table output (analogous to the DESCRIBE|developer-guide/ksqldb-reference/describe/
command in the ksqlDB CLI)
- Jump to the ksqlDB Editor page to query the table.
- Drop a table (analogous to the DROP TABLE|developer-guide/ksqldb-reference/drop-table/
command in the ksqlDB CLI).
Click a table to view its information, like the table name, associated Kafka
topic, number of partitions and replicas, and the data format.
Running Queries
To access the Running Queries page, click the ksqlDB application name
in the ksqlDB applications page and click the Running Queries tab.
Use the Running Queries page to:
- View the syntax and details of running queries.
- Search running queries.
- View the query execution plan by clicking Explain (analogous to the EXPLAIN
command in the ksqlDB CLI).
- Terminate a running query.
Click Persistent Query Examples to view the ksqlDB examples available in Kafka Tutorials.
Tip
Go through the Confluent Platform Local or Docker
quick start guides for a fast set up
of streams, tables, and persisted running queries in Control Center.
Flow View
To access the Flow View page, click the ksqlDB cluster name
in the ksqlDB applications page and click the Flow tab.
Use Flow View to:
- View the topology of your ksqlDB application.
- Inspect the details of streams, tables, and the ksqlDB statements that
create them.
- View events as they flow through your application.
Click a node in the graph to see details about the topology of your ksqlDB
application. For example, click on a stream to see its schema and the messages
as they arrive in realtime.
Enable and disable the ksqlDB feature in Control Center
The ksqlDB feature is enabled by default. The feature can be disabled by setting
the confluent.controlcenter.ksql.enable
option in the Control Center properties
file to false
. After disabling the feature, the ksqlDB submenu in the Cluster
navigation is no longer visible in the Control Center UI. You can disable the setting
if you are not using RBAC in Control Center or ksqlDB, and you do not want anyone
to access the ksqlDB feature.
Important
If RBAC is enabled for Control Center,
it takes precedence over Access Control settings.
To disable the ksqlDB feature in Control Center:
Set the confluent.controlcenter.ksql.enable
option in your
control-center.properties
file to false
.
...
confluent.controlcenter.ksql.enable=false
...
Note
Make the change in the appropriate Control Center properties files
configured for your environments, including
control-center-dev.properties
or
control-center-production.properties
. The properties files are
located in /path-to-confluent/etc/confluent-control-center/
.
Restart Control Center and pass in the properties file for the configuration to
take effect.
Local (dev) environment:
confluent local services control-center stop
confluent local services control-center start --config="../etc/confluent-control-center/control-center.properties"
Production environment:
./bin/control-center-stop
./bin/control-center-start ../etc/confluent-control-center/control-center.properties
To enable the feature again, set the option back to true
and restart
Control Center with the updated properties file.