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 toolkit for connecting to and querying a ClickHouse database. Enables schema discovery, table inspection, and read-only SQL execution against any ClickHouse instance.
Capabilities
- Schema & structure discovery: List all databases, enumerate tables, and retrieve individual table schemas before querying.
- Read-only query execution: Run
SELECTstatements with structured clause composition (joins, filters, ordering, pagination); non-read operations (INSERT,UPDATE,DELETE) are blocked. - Query safety guardrails: Built-in rules enforce column-level selection (no
SELECT *), case-insensitive string matching, string trimming,LIKE-based matching, and index-aware joins to reduce runtime errors.
Secrets
CLICKHOUSE_DATABASE_CONNECTION_STRING — The full connection string used to authenticate and connect to your ClickHouse instance. The format is typically a DSN or URL such as clickhouse://[user]:[password]@[host]:[port]/[database]. Obtain this from your ClickHouse deployment details:
- Self-hosted: Construct it from your server's host, port (default
9000for native or8123for HTTP), database name, and credentials set during installation or inusers.xml. - ClickHouse Cloud: Find the connection string in your ClickHouse Cloud console under Services → Connect. Select the driver/protocol you need, and the console will populate the host, port, and user fields. Use the password you set when creating the service (or reset it from the same page).
For guidance on storing secrets in Arcade, see the Arcade secrets documentation and manage 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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