Clickhouse
Tools to query and explore a ClickHouse database
1.0.2ClickHouse Toolkit
Arcade's ClickHouse toolkit connects agents to a ClickHouse database, enabling read-only exploration and querying of its structure and data.
Capabilities
- Schema discovery: List all databases, retrieve available tables, and inspect individual table schemas before querying.
- Read-only querying: Execute
SELECTstatements with support for joins, filters, ordering, pagination, and aggregation — no write operations permitted. - Query safety guardrails: Built-in rules enforce column-explicit selects, case-insensitive string matching, string trimming, index-aware joins, and mandatory result ordering to reduce runtime errors.
Secrets
CLICKHOUSE_DATABASE_CONNECTION_STRING — The full connection string used to authenticate and connect to your ClickHouse instance. It encodes the protocol, credentials, host, port, and target database in a single URI, typically in the form clickhouse://[user]:[password]@[host]:[port]/[database] (or the clickhouses:// variant for TLS). Obtain this from your ClickHouse deployment details: for ClickHouse Cloud, find the connection info in the ClickHouse Cloud console under your service's Connect tab; for self-hosted instances, assemble it from your server configuration. Ensure the user has at minimum SELECT and SHOW privileges on the target database.
For help configuring secrets in Arcade, see the secrets guide or manage them 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 |