Clickhouse
Community
Tools to query and explore a ClickHouse database
Author:Arcade
Version:
1.0.2Auth:No authentication required
5tools
5require secrets
ClickHouse Toolkit
Arcade's ClickHouse toolkit connects agents to a ClickHouse database, enabling schema discovery and read-only SQL querying.
Capabilities
- Database & table discovery: Enumerate available databases, list tables, and retrieve table schemas before querying — enforced as a required workflow step.
- Read-only query execution: Run
SELECTstatements with structured clause inputs (select, from, join, where, having, order by, limit, offset); insert/update/delete operations are blocked. - Query safety guardrails: Built-in rules encourage indexed joins, case-insensitive string matching, column-explicit selects, and trimmed string comparisons to reduce runtime errors against ClickHouse's case-sensitive engine.
- Schema introspection: Retrieve column definitions and structure for any named table to inform accurate query construction.
Secrets
CLICKHOUSE_DATABASE_CONNECTION_STRING — The full connection string used to authenticate and connect to your ClickHouse instance. This typically follows the format clickhouse://[user]:[password]@[host]:[port]/[database] (or the HTTP-equivalent DSN depending on the driver). Obtain this from your ClickHouse deployment:
- ClickHouse Cloud: Log in to the ClickHouse Cloud console, select your service, and find the connection details under Connect. Copy the native protocol or HTTP endpoint and assemble the DSN with your username and password.
- Self-hosted: Use the host/port configured in your
config.xmlor environment, along with a user account created viaCREATE USERwith appropriateSELECTgrants on the target database.
Store this value as an Arcade secret. See the Arcade secrets guide for setup instructions, and manage stored secrets at https://api.arcade.dev/dashboard/auth/secrets.
Available tools(5)
5 of 5 tools
Operations
Behavior
| 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 |
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