Mcp Clickhouse

What is Mcp Clickhouse about?

Mcp Clickhouse is an MCP server that exposes ClickHouse and chDB functionality as callable tools. It enables AI assistants to safely execute read‑only SQL queries, list databases and tables, and query data directly from files or URLs without needing an ETL step.

How to use Mcp Clickhouse?

1. Installation – install the package from PyPI (python3 -m pip install mcp-clickhouse) or run it via uv in a virtual environment.
2. Configuration – set required environment variables (CLICKHOUSE_HOST, CLICKHOUSE_USER, CLICKHOUSE_PASSWORD) and optional ones (port, TLS settings, timeouts) in your Claude Desktop config or a .env file. Enable chDB with CHDB_ENABLED=true if desired.
3. Running – start the server with the chosen transport (stdio, http, or sse). For HTTP, the server listens on port 8000 by default and exposes /mcp for tool calls and /health for health checks.
4. Calling Tools – AI assistants can invoke run_select_query, list_databases, list_tables, or run_chdb_select_query with the appropriate parameters.

Key features of Mcp Clickhouse

• ClickHouse Tools
  • run_select_query: execute read‑only queries.
  • list_databases: enumerate databases.
  • list_tables: enumerate tables in a database.
• chDB Tools
  • run_chdb_select_query: run queries using the embedded ClickHouse engine, reading directly from files, URLs, or other sources.
• Health Check Endpoint – /health returns ClickHouse version when healthy, otherwise HTTP 503.
• Flexible Transport – supports stdio, HTTP, and SSE transports for local development or remote deployment.
• Configurable TLS & Timeouts – fine‑tune security and connectivity.

Use cases of Mcp Clickhouse

• Data exploration: let AI assistants explore large analytical datasets in ClickHouse without exposing write permissions.
• Ad‑hoc reporting: generate on‑the‑fly reports by issuing SELECT statements via conversational interfaces.
• File‑based analytics: query CSV, Parquet, or other files directly with chDB, avoiding separate ingestion pipelines.
• Monitoring: integrate the health endpoint into orchestration tools to ensure the MCP server can reach ClickHouse.

FAQ from the Mcp Clickhouse

• Do queries run with write permissions? No, all ClickHouse queries are executed with readonly = 1.
• Can I disable ClickHouse and use only chDB? Yes, set CLICKHOUSE_ENABLED=false and CHDB_ENABLED=true.
• What transport should I use for production? HTTP or SSE is recommended for networked deployments; stdio is convenient for local testing.
• How do I secure the connection? Enable TLS with CLICKHOUSE_SECURE=true and keep CLICKHOUSE_VERIFY enabled unless you have a specific reason to disable it.
• Is there a way to run the server without uv? Absolutely – install via pip and start with python3 -m mcp_clickhouse.main or the installed mcp-clickhouse script.

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

YouTube Overview