Clickhouse
Tools to query and explore a ClickHouse database
1.0.2ClickHouse Toolkit
Arcade toolkit for querying and exploring a ClickHouse database. Enables agents to discover database structure and execute read-only SQL queries against a ClickHouse instance.
Capabilities
- Schema discovery: List databases, enumerate tables, and retrieve individual table schemas before constructing queries.
- Read-only query execution: Run structured
SELECTqueries with support for joins, filtering, ordering, pagination, and aggregation;INSERT,UPDATE,DELETE, and other mutations are blocked. - Query safety guardrails: Built-in rules enforce column-specific selects, case-insensitive string matching, string trimming,
LIKE-based matching, and index/primary-key-only joins to reduce runtime errors.
Secrets
CLICKHOUSE_DATABASE_CONNECTION_STRING — The full connection string used to authenticate and connect to your ClickHouse instance. This typically follows the format clickhouse+native://user:password@host:port/database (for native protocol) or clickhouse+http://user:password@host:port/database (for HTTP). You obtain this by noting the host, port, database name, and credentials configured for your ClickHouse deployment. For ClickHouse Cloud, find the connection details in the ClickHouse Cloud console under your service's Connect tab. For self-hosted instances, refer to your server's config.xml or the administrator who provisioned the instance. Ensure the user account has at minimum SELECT privileges on the target databases.
For guidance on registering secrets with Arcade, see Create Tool Secrets. You can also manage secrets directly at https://api.arcade.dev/dashboard/auth/secrets.
Available tools(5)
| Tool name | Description | Secrets | |
|---|---|---|---|
Discover all the databases in the ClickHouse database. | 1 | ||
Discover all the schemas in the ClickHouse database.
Note: ClickHouse doesn't have schemas like PostgreSQL, so this returns a default schema name. | 1 | ||
Discover all the tables in the ClickHouse database when the list of tables is not known.
ALWAYS use this tool before any other tool that requires a table name. | 1 | ||
You have a connection to a ClickHouse database.
Execute a SELECT query and return the results against the ClickHouse database.
No other queries (INSERT, UPDATE, DELETE, etc.) are allowed.
ONLY use this tool if you have already loaded the schema of the tables you need to query.
The final query will be constructed as follows:
SELECT {select_query_part} FROM {from_clause} JOIN {join_clause}
WHERE {where_clause} HAVING {having_clause}
ORDER BY {order_by_clause} LIMIT {limit} OFFSET {offset}
When running queries, follow these rules which will help avoid errors:
* Never "select *" from a table. Always select the columns you need.
* Always order your results. Use the most important columns or the primary key if you're unsure.
* Always use case-insensitive queries to match strings in the query.
* Always trim strings in the query.
* Prefer LIKE queries over direct string matches or regex queries.
* Only join on columns that are indexed or the primary key. Do not join on arbitrary columns.
* ClickHouse is case-sensitive, so be careful with table and column names. | 1 | ||
Get the schema/structure of a ClickHouse table in the ClickHouse database
when the schema is not known, and the name of the table is provided.
This tool should ALWAYS be used before executing any query.
All tables in the query must be discovered first,
so that their exact names are known. | 1 |