ClickHouse MCP Server

What is ClickHouse MCP Server about?

Provides an MCP server that connects AI assistants to a ClickHouse cluster (or the embedded chDB engine). It exposes tools for executing safe, read‑only SQL statements, retrieving schema information, and performing ad‑hoc analysis without requiring ETL pipelines.

How to use ClickHouse MCP Server?

1. Install the package from PyPI:

   python3 -m pip install mcp-clickhouse
   

   Or install via uv for an isolated environment.
2. Configure the server in Claude Desktop (or any MCP client) by setting environment variables such as CLICKHOUSE_HOST, CLICKHOUSE_USER, CLICKHOUSE_PASSWORD, and optional flags (CLICKHOUSE_SECURE, CHDB_ENABLED, etc.).
3. Start the server using the chosen transport (stdio, http, or sse). For HTTP transport:

   CLICKHOUSE_MCP_SERVER_TRANSPORT=http python -m mcp_clickhouse.main
   

   The health‑check endpoint is available at /health.
4. Invoke the exposed tools (run_select_query, list_databases, list_tables, run_chdb_select_query) from your AI assistant via the MCP protocol.

Key Features

• run_select_query – Execute read‑only SQL on ClickHouse (readonly = 1).
• list_databases – Retrieve all databases.
• list_tables – List tables in a specified database.
• run_chdb_select_query – Query data directly via the embedded chDB engine (files, URLs, etc.).
• Health‑check endpoint – /health returns ClickHouse version or service‑unavailable status.
• Flexible transport options: stdio, HTTP, SSE.
• Ability to enable ClickHouse, chDB, or both simultaneously.

Use Cases

• Data‑driven AI assistants that need on‑demand analytics from a ClickHouse warehouse.
• Rapid prototyping of SQL‑based queries within chat interfaces without building custom back‑ends.
• Ad‑hoc reporting from files or URLs using chDB’s zero‑ETL capabilities.
• Monitoring of ClickHouse connectivity via the health endpoint.

FAQ

• Do queries run with write privileges? No. All ClickHouse queries are forced to readonly = 1.
• Can I use the server without uv? Yes. Install via pip and run with python -m mcp_clickhouse.main or the generated mcp-clickhouse script.
• What ports are used for HTTP transport? Default is 8000; customize with CLICKHOUSE_MCP_BIND_PORT.
• How to enable only chDB? Set CHDB_ENABLED=true and CLICKHOUSE_ENABLED=false in the environment.
• Is SSL verification required? Enabled by default (CLICKHOUSE_VERIFY=true); can be disabled for local testing.

ClickHouse MCP Server

An MCP server for ClickHouse.

Features

ClickHouse Tools

• run_select_query

  • Execute SQL queries on your ClickHouse cluster.
  • Input: sql (string): The SQL query to execute.
  • All ClickHouse queries are run with readonly = 1 to ensure they are safe.

• list_databases

  • List all databases on your ClickHouse cluster.

• list_tables

  • List all tables in a database.
  • Input: database (string): The name of the database.

chDB Tools

• run_chdb_select_query
  • Execute SQL queries using chDB's embedded ClickHouse engine.
  • Input: sql (string): The SQL query to execute.
  • Query data directly from various sources (files, URLs, databases) without ETL processes.

Health Check Endpoint

When running with HTTP or SSE transport, a health check endpoint is available at /health. This endpoint:

• Returns 200 OK with the ClickHouse version if the server is healthy and can connect to ClickHouse
• Returns 503 Service Unavailable if the server cannot connect to ClickHouse

Example:

curl http://localhost:8000/health
# Response: OK - Connected to ClickHouse 24.3.1

Configuration

This MCP server supports both ClickHouse and chDB. You can enable either or both depending on your needs.

1. Open the Claude Desktop configuration file located at:

   • On macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
   • On Windows: %APPDATA%/Claude/claude_desktop_config.json

2. Add the following:

{
  "mcpServers": {
    "mcp-clickhouse": {
      "command": "uv",
      "args": [
        "run",
        "--with",
        "mcp-clickhouse",
        "--python",
        "3.10",
        "mcp-clickhouse"
      ],
      "env": {
        "CLICKHOUSE_HOST": "<clickhouse-host>",
        "CLICKHOUSE_PORT": "<clickhouse-port>",
        "CLICKHOUSE_USER": "<clickhouse-user>",
        "CLICKHOUSE_PASSWORD": "<clickhouse-password>",
        "CLICKHOUSE_SECURE": "true",
        "CLICKHOUSE_VERIFY": "true",
        "CLICKHOUSE_CONNECT_TIMEOUT": "30",
        "CLICKHOUSE_SEND_RECEIVE_TIMEOUT": "30"
      }
    }
  }
}

Update the environment variables to point to your own ClickHouse service.

Or, if you'd like to try it out with the ClickHouse SQL Playground, you can use the following config:

{
  "mcpServers": {
    "mcp-clickhouse": {
      "command": "uv",
      "args": [
        "run",
        "--with",
        "mcp-clickhouse",
        "--python",
        "3.10",
        "mcp-clickhouse"
      ],
      "env": {
        "CLICKHOUSE_HOST": "sql-clickhouse.clickhouse.com",
        "CLICKHOUSE_PORT": "8443",
        "CLICKHOUSE_USER": "demo",
        "CLICKHOUSE_PASSWORD": "",
        "CLICKHOUSE_SECURE": "true",
        "CLICKHOUSE_VERIFY": "true",
        "CLICKHOUSE_CONNECT_TIMEOUT": "30",
        "CLICKHOUSE_SEND_RECEIVE_TIMEOUT": "30"
      }
    }
  }
}

For chDB (embedded ClickHouse engine), add the following configuration:

{
  "mcpServers": {
    "mcp-clickhouse": {
      "command": "uv",
      "args": [
        "run",
        "--with",
        "mcp-clickhouse",
        "--python",
        "3.10",
        "mcp-clickhouse"
      ],
      "env": {
        "CHDB_ENABLED": "true",
        "CLICKHOUSE_ENABLED": "false",
        "CHDB_DATA_PATH": "/path/to/chdb/data"
      }
    }
  }
}

You can also enable both ClickHouse and chDB simultaneously:

{
  "mcpServers": {
    "mcp-clickhouse": {
      "command": "uv",
      "args": [
        "run",
        "--with",
        "mcp-clickhouse",
        "--python",
        "3.10",
        "mcp-clickhouse"
      ],
      "env": {
        "CLICKHOUSE_HOST": "<clickhouse-host>",
        "CLICKHOUSE_PORT": "<clickhouse-port>",
        "CLICKHOUSE_USER": "<clickhouse-user>",
        "CLICKHOUSE_PASSWORD": "<clickhouse-password>",
        "CLICKHOUSE_SECURE": "true",
        "CLICKHOUSE_VERIFY": "true",
        "CLICKHOUSE_CONNECT_TIMEOUT": "30",
        "CLICKHOUSE_SEND_RECEIVE_TIMEOUT": "30",
        "CHDB_ENABLED": "true",
        "CHDB_DATA_PATH": "/path/to/chdb/data"
      }
    }
  }
}

3. Locate the command entry for uv and replace it with the absolute path to the uv executable. This ensures that the correct version of uv is used when starting the server. On a mac, you can find this path using which uv.

4. Restart Claude Desktop to apply the changes.

Running Without uv (Using System Python)

If you prefer to use the system Python installation instead of uv, you can install the package from PyPI and run it directly:

1. Install the package using pip:

   python3 -m pip install mcp-clickhouse
   

   To upgrade to the latest version:

   python3 -m pip install --upgrade mcp-clickhouse
   

2. Update your Claude Desktop configuration to use Python directly:

{
  "mcpServers": {
    "mcp-clickhouse": {
      "command": "python3",
      "args": [
        "-m",
        "mcp_clickhouse.main"
      ],
      "env": {
        "CLICKHOUSE_HOST": "<clickhouse-host>",
        "CLICKHOUSE_PORT": "<clickhouse-port>",
        "CLICKHOUSE_USER": "<clickhouse-user>",
        "CLICKHOUSE_PASSWORD": "<clickhouse-password>",
        "CLICKHOUSE_SECURE": "true",
        "CLICKHOUSE_VERIFY": "true",
        "CLICKHOUSE_CONNECT_TIMEOUT": "30",
        "CLICKHOUSE_SEND_RECEIVE_TIMEOUT": "30"
      }
    }
  }
}

Alternatively, you can use the installed script directly:

{
  "mcpServers": {
    "mcp-clickhouse": {
      "command": "mcp-clickhouse",
      "env": {
        "CLICKHOUSE_HOST": "<clickhouse-host>",
        "CLICKHOUSE_PORT": "<clickhouse-port>",
        "CLICKHOUSE_USER": "<clickhouse-user>",
        "CLICKHOUSE_PASSWORD": "<clickhouse-password>",
        "CLICKHOUSE_SECURE": "true",
        "CLICKHOUSE_VERIFY": "true",
        "CLICKHOUSE_CONNECT_TIMEOUT": "30",
        "CLICKHOUSE_SEND_RECEIVE_TIMEOUT": "30"
      }
    }
  }
}

Note: Make sure to use the full path to the Python executable or the mcp-clickhouse script if they are not in your system PATH. You can find the paths using:

• which python3 for the Python executable
• which mcp-clickhouse for the installed script

Development

1. In test-services directory run docker compose up -d to start the ClickHouse cluster.

2. Add the following variables to a .env file in the root of the repository.

Note: The use of the default user in this context is intended solely for local development purposes.

CLICKHOUSE_HOST=localhost
CLICKHOUSE_PORT=8123
CLICKHOUSE_USER=default
CLICKHOUSE_PASSWORD=clickhouse

3. Run uv sync to install the dependencies. To install uv follow the instructions here. Then do source .venv/bin/activate.

4. For easy testing with the MCP Inspector, run fastmcp dev mcp_clickhouse/mcp_server.py to start the MCP server.

5. To test with HTTP transport and the health check endpoint:

   # Using default port 8000
   CLICKHOUSE_MCP_SERVER_TRANSPORT=http python -m mcp_clickhouse.main
   
   # Or with a custom port
   CLICKHOUSE_MCP_SERVER_TRANSPORT=http CLICKHOUSE_MCP_BIND_PORT=4200 python -m mcp_clickhouse.main
   
   # Then in another terminal:
   curl http://localhost:8000/health  # or http://localhost:4200/health for custom port
   

Environment Variables

The following environment variables are used to configure the ClickHouse and chDB connections:

ClickHouse Variables

Required Variables

• CLICKHOUSE_HOST: The hostname of your ClickHouse server
• CLICKHOUSE_USER: The username for authentication
• CLICKHOUSE_PASSWORD: The password for authentication

[!CAUTION] It is important to treat your MCP database user as you would any external client connecting to your database, granting only the minimum necessary privileges required for its operation. The use of default or administrative users should be strictly avoided at all times.

Optional Variables

• CLICKHOUSE_PORT: The port number of your ClickHouse server
  • Default: 8443 if HTTPS is enabled, 8123 if disabled
  • Usually doesn't need to be set unless using a non-standard port
• CLICKHOUSE_SECURE: Enable/disable HTTPS connection
  • Default: "true"
  • Set to "false" for non-secure connections
• CLICKHOUSE_VERIFY: Enable/disable SSL certificate verification
  • Default: "true"
  • Set to "false" to disable certificate verification (not recommended for production)
• CLICKHOUSE_CONNECT_TIMEOUT: Connection timeout in seconds
  • Default: "30"
  • Increase this value if you experience connection timeouts
• CLICKHOUSE_SEND_RECEIVE_TIMEOUT: Send/receive timeout in seconds
  • Default: "300"
  • Increase this value for long-running queries
• CLICKHOUSE_DATABASE: Default database to use
  • Default: None (uses server default)
  • Set this to automatically connect to a specific database
• CLICKHOUSE_MCP_SERVER_TRANSPORT: Sets the transport method for the MCP server.
  • Default: "stdio"
  • Valid options: "stdio", "http", "sse". This is useful for local development with tools like MCP Inspector.
• CLICKHOUSE_MCP_BIND_HOST: Host to bind the MCP server to when using HTTP or SSE transport
  • Default: "127.0.0.1"
  • Set to "0.0.0.0" to bind to all network interfaces (useful for Docker or remote access)
  • Only used when transport is "http" or "sse"
• CLICKHOUSE_MCP_BIND_PORT: Port to bind the MCP server to when using HTTP or SSE transport
  • Default: "8000"
  • Only used when transport is "http" or "sse"
• CLICKHOUSE_ENABLED: Enable/disable ClickHouse functionality
  • Default: "true"
  • Set to "false" to disable ClickHouse tools when using chDB only

chDB Variables

• CHDB_ENABLED: Enable/disable chDB functionality
  • Default: "false"
  • Set to "true" to enable chDB tools
• CHDB_DATA_PATH: The path to the chDB data directory
  • Default: ":memory:" (in-memory database)
  • Use :memory: for in-memory database
  • Use a file path for persistent storage (e.g., /path/to/chdb/data)

Example Configurations

For local development with Docker:

# Required variables
CLICKHOUSE_HOST=localhost
CLICKHOUSE_USER=default
CLICKHOUSE_PASSWORD=clickhouse

# Optional: Override defaults for local development
CLICKHOUSE_SECURE=false  # Uses port 8123 automatically
CLICKHOUSE_VERIFY=false

For ClickHouse Cloud:

# Required variables
CLICKHOUSE_HOST=your-instance.clickhouse.cloud
CLICKHOUSE_USER=default
CLICKHOUSE_PASSWORD=your-password

# Optional: These use secure defaults
# CLICKHOUSE_SECURE=true  # Uses port 8443 automatically
# CLICKHOUSE_DATABASE=your_database

For ClickHouse SQL Playground:

CLICKHOUSE_HOST=sql-clickhouse.clickhouse.com
CLICKHOUSE_USER=demo
CLICKHOUSE_PASSWORD=
# Uses secure defaults (HTTPS on port 8443)

For chDB only (in-memory):

# chDB configuration
CHDB_ENABLED=true
CLICKHOUSE_ENABLED=false
# CHDB_DATA_PATH defaults to :memory:

For chDB with persistent storage:

# chDB configuration
CHDB_ENABLED=true
CLICKHOUSE_ENABLED=false
CHDB_DATA_PATH=/path/to/chdb/data

For MCP Inspector or remote access with HTTP transport:

CLICKHOUSE_HOST=localhost
CLICKHOUSE_USER=default
CLICKHOUSE_PASSWORD=clickhouse
CLICKHOUSE_MCP_SERVER_TRANSPORT=http
CLICKHOUSE_MCP_BIND_HOST=0.0.0.0  # Bind to all interfaces
CLICKHOUSE_MCP_BIND_PORT=4200  # Custom port (default: 8000)

When using HTTP transport, the server will run on the configured port (default 8000). For example, with the above configuration:

• MCP endpoint: http://localhost:4200/mcp
• Health check: http://localhost:4200/health

You can set these variables in your environment, in a .env file, or in the Claude Desktop configuration:

{
  "mcpServers": {
    "mcp-clickhouse": {
      "command": "uv",
      "args": [
        "run",
        "--with",
        "mcp-clickhouse",
        "--python",
        "3.10",
        "mcp-clickhouse"
      ],
      "env": {
        "CLICKHOUSE_HOST": "<clickhouse-host>",
        "CLICKHOUSE_USER": "<clickhouse-user>",
        "CLICKHOUSE_PASSWORD": "<clickhouse-password>",
        "CLICKHOUSE_DATABASE": "<optional-database>",
        "CLICKHOUSE_MCP_SERVER_TRANSPORT": "stdio",
        "CLICKHOUSE_MCP_BIND_HOST": "127.0.0.1",
        "CLICKHOUSE_MCP_BIND_PORT": "8000"
      }
    }
  }
}

Note: The bind host and port settings are only used when transport is set to "http" or "sse".

Running tests

uv sync --all-extras --dev # install dev dependencies
uv run ruff check . # run linting

docker compose up -d test_services # start ClickHouse
uv run pytest -v tests
uv run pytest -v tests/test_tool.py # ClickHouse only
uv run pytest -v tests/test_chdb_tool.py # chDB only

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