How to Connect ClickHouse to Looker

Galaxy Glossary

How do I connect ClickHouse to Looker?

Configure Looker to query ClickHouse through a JDBC connection string, set up SSL, and verify schema access.

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Description

Example H2

Example H3

What connection settings does Looker require for ClickHouse?

Provide Host, Port (default 8123 for HTTP or 9000 for native), Database, Username, Password, and JDBC Parameters. Set Dialect to clickhouse in Looker’s Admin → Connections panel.

How do I write the JDBC URL?

Use jdbc:clickhouse://HOST:PORT/DATABASE?user=USER&password=PWD&ssl=true&sslmode=none. Replace placeholders with actual values. ssl=true avoids plain-text credentials.

Should I use HTTP or Native port?

Pick 8123 (HTTP) for ease or 9440 for HTTPS. Use 9000 only if Looker’s dialect supports native port in your version.Always match protocol and port.

How do I test the connection?

Click “Test” in Looker. A green check means Looker can authenticate, open the schema, and run SELECT 1 on ClickHouse.

How do I model ClickHouse tables in LookML?

Create a view for each fact or dimension. Reference ClickHouse tables directly, e.g., sql_table_name: Orders ;;. Use LookML derived tables for aggregates.

What performance tweaks help?

Set connect_timeout and socket_timeout JDBC parameters to 30 000 ms. Enable max_execution_time for runaway queries.Use materialized views in ClickHouse for Looker Explores.

Why How to Connect ClickHouse to Looker is important

How to Connect ClickHouse to Looker Example Usage


SELECT customer_id,
       sum(total_amount)        AS lifetime_value,
       count()                  AS order_count
FROM Orders
GROUP BY customer_id
ORDER BY lifetime_value DESC
LIMIT 10;

How to Connect ClickHouse to Looker Syntax


jdbc:clickhouse://<HOST>:<PORT>/<DATABASE>?user=<USERNAME>&password=<PASSWORD>[&ssl=<true|false>][&sslmode=<mode>]

-- Example
jdbc:clickhouse://analytics.myshop.com:9440/production?user=looker&password=s3cret&ssl=true&sslmode=none

Common Mistakes

Using the HTTP port 8123 without HTTPS: data travels unencrypted. Fix by proxying through 9440 with SSL enabled or by adding ssl=true in the connection string.
Omitting the database name in the JDBC URL: Looker fails to find tables. Always append /<DATABASE> right after the host and port.