🔌Add a ClickHouse connector

Connector features

This data connector is compatible with NativeSQL with our new data execution system

Configuring a ClickHouse connection¶

You can use the Toucan ClickHouse connector to connect to your ClickHouse cluster with a basic authentication and access tables with a SQL query.

With this connection, you can fetch data from your ClickHouse to fill your charts and dashboards.

Changelog

September 25 - This connector is supported by our new Data execution system

Configuring a ClickHouse connection¶

Follow the steps described in Add a connector, choose ClickHouse and fill out the form with the following info:

Field	Format / Type	Description	Example
Name (mandatory)	String	Use it to identify your connection	my_clickhouse_connector
Host (mandatory)	String	could be an IP address or an hostname (e.g localhost)	"db.example.com" or "192.168.1.100"
Port (mandatory)	Integer	an integer, by default ClickHouse runs on port 9000	9000 (default)
User (mandatory)	String	Your login user	db_user
Password (mandatory)	String	Your login password (this value will be stored as a secret)	abcD1234
SSL_connection (optional)	Boolean	Allow to enable to enable SSL wrapped TCP connection, to enable if your Toucan workspace and your ClickHouse cluster are not in the same network
Retry Policy (optional)	Boolean	Boolean allows to configure a retry policy if the connection is flaky. max attempts: maximum number of retries before giving up max_delay: in seconds, above the connection is dropped wait_time: time in seconds between each retry
Slow Queries' Cache Expiration Time (optional)	Integer	Slow queries' cache expiration time in seconds

Click on the SAVE button to add the connection

After successfully configuring the connector, you will be able to find it in the Connector section of the DataHub "Datasource" tab

Create a dataset from a ClickHouse connection

This data connector is only supported in code/SQL mode

Fill the mandatory fields:

• Simple mode

  • Database, a dropdown list of available databases

  • Table, a drop down list of available tables. The list will be populated only when a database is selected.

  • columns, a drop down list of available columns, we will select only the columns you checked

• Alternatively, in SQL/code mode

  • Database, a dropdown list of available databases

  • in the Query content section a SQL query field, where you can write your SQL query, if left blank a select * from Table limit 50 will run

How to troubleshoot a ClickHouse connection

If a warning icon appears after adding a ClickHouse connection, it indicates that Toucan cannot establish a stable connection to your ClickHouse cluster. In this case if you try to create a new dataset from this connector, you will not be able to pick a database from the dropdown (a detailedHttpError will be displayed when landing on the UI)

Mandatory fields

Ensure all mandatory fields (Name, Host, Port, User, Password) are filled.

Network access

• Verify that the Host (IP or DNS) is reachable from Toucan IP and is not blocked by firewalls.

Check our IP for our Current Data Execution System and New Data Execution System

• Check that the Port (default is 9000) matches the ClickHouse cluster's configuration and is open.

Authentication

• Confirm User and Password are valid and have been granted connect permissions to the target database.

Other options

Connect timeout

• Adjust Connect Timeout if timeouts occur, especially in remote or slow network situations.

Advanced troubleshooting

• Review logs on PostgreSQL server for more detailed error information.

• For persistent issues, attempt to connect using CLI with the same parameters to isolate issues.