ClickHouse
Connect Semaphor to your ClickHouse instance
Prerequisites
Before you connect Semaphor to ClickHouse, ensure the following requirements are met.
Database Permissions
- The user must have read access to the necessary tables.
- The user must be able to query information_schema table to retrieve metadata.
Required Permissions
To fetch metadata (such as column names and types), your database user must have the following privilege:
GRANT SELECT(column_name, data_type, table_catalog, table_name) ON information_schema.columns
Without this, you may see an ACCESS_DENIED error when trying to run queries or introspect schemas.
Connecting to ClickHouse
To connect Semaphor to your ClickHouse instance, use a connection string in the following format.
Connection String Format
username– Your database username.password– The corresponding password.host– The hostname or IP address of your ClickHouse instance.port- Your database port. If not specified, the default port (8443) will be used.database- Your target database. This is necessary since Clickhouse connector doesn't support multi-line SQL statements. Ex.use mydatabase; select * from table.
Example Connection String
If your ClickHouse user is default, your password is mypassword, and your host is instance.us-east-1.aws.clickhouse.cloud, your connection string will be:
Network Access
- If your database is private, whitelist the Semaphor IP:
44.199.53.142to allow connections. - Make sure your firewall rules and security groups allow inbound connections from Semaphor.
Troubleshooting
If you encounter issues connecting to Clickhouse, review the following:
- Invalid Credentials: Verify your username and password.
- Network Restrictions: Confirm that your server accepts connections from Semaphor’s IP address.
- Incorrect Connection String: Double-check that your connection string matches the required format.
- Database Permissions: Make sure your database user has permission to query the necessary tables and metadata.
If you continue to experience issues, contact Semaphor Support for assistance.