QuestDB MCP Server
A Model Context Protocol (MCP) server for QuestDB that enables AI assistants to interact with QuestDB databases through tools for querying and inserting data.
Features
- Query Execution: Execute SELECT queries on QuestDB tables with structured output
- Data Insertion: Insert data into QuestDB tables using the InfluxDB Line Protocol
- Table Management: List tables and describe table schemas
- Automatic Schema Creation: Tables and columns are created automatically on insert
- Type Safety: Full TypeScript support with Zod schema validation
- Structured Output: All tools return structured content with output schemas
- MCP Logging: Integrated MCP logging messages for better observability
- Error Handling: Comprehensive error handling with graceful degradation
- Server Instructions: Built-in server instructions for AI assistants
- Graceful Shutdown: Proper cleanup on SIGINT/SIGTERM signals
Prerequisites
- Node.js v16 or newer
- QuestDB instance running (see QuestDB Quick Start)
Installation
As a Package
Install from npm:
npm install questdbmcp
Note: This package is publicly available on npm. No authentication or configuration is required to install or use it.
From Source
-
Clone this repository or navigate to the project directory:
cd questdbmcp -
Install dependencies:
npm install -
Build the project:
npm run build
Configuration
The server can be configured using environment variables:
QUESTDB_HOST- QuestDB host (default:localhost)QUESTDB_PORT- QuestDB port (default:9000)QUESTDB_USERNAME- QuestDB username (optional, for authentication)QUESTDB_PASSWORD- QuestDB password (optional, for authentication)QUESTDB_AUTO_FLUSH_ROWS- Auto-flush after N rows (optional)QUESTDB_AUTO_FLUSH_INTERVAL- Auto-flush interval in milliseconds (optional)
Usage
This package can be used in two ways:
1. CLI Usage
Run the MCP server directly:
npm start
Or for development:
npm run dev
Or install globally:
npm install -g questdbmcp
questdbmcp
2. Library Usage
Install as a dependency in your TypeScript project:
npm install questdbmcp
Basic Usage
import { QuestDBMCPServer, loadConfig } from 'questdbmcp';
// Load configuration from environment variables
const config = loadConfig();
// Create server instance
const server = new QuestDBMCPServer(config);
// Start the server
await server.run();
Custom Configuration
import { QuestDBMCPServer, QuestDBConfig } from 'questdbmcp';
const config: QuestDBConfig = {
host: 'localhost',
port: 9000,
username: 'admin',
password: 'quest',
};
const server = new QuestDBMCPServer(config, {
setupProcessHandlers: false, // Don't set up process handlers when using as library
serverName: 'my-questdb-server',
serverVersion: '1.0.0',
instructions: 'Custom server instructions...',
});
await server.run();
Using with Custom Transport
import { QuestDBMCPServer, QuestDBConfig } from 'questdbmcp';
import { StreamableHTTPServerTransport } from '@modelcontextprotocol/sdk/server/streamableHttp.js';
import express from 'express';
const config: QuestDBConfig = {
host: 'localhost',
port: 9000,
};
const server = new QuestDBMCPServer(config, {
setupProcessHandlers: false,
});
const app = express();
app.use(express.json());
app.post('/mcp', async (req, res) => {
const transport = new StreamableHTTPServerTransport({
sessionIdGenerator: undefined,
enableJsonResponse: true,
});
res.on('close', () => {
transport.close();
});
await server.server.connect(transport);
await transport.handleRequest(req, res, req.body);
});
app.listen(3000, () => {
console.log('MCP server running on http://localhost:3000/mcp');
});
Accessing Internal Components
import { QuestDBMCPServer } from 'questdbmcp';
const server = new QuestDBMCPServer(config);
// Access the underlying MCP server
const mcpServer = server.server;
// Access the QuestDB client
const client = server.questDBClient;
// Access the logger
const logger = server.log;
// Use the client directly
const tables = await client.listTables();
const result = await client.query('SELECT * FROM my_table LIMIT 10');
// Use the logger
await logger.info('Custom log message', { metadata: 'value' });
Creating Custom Tools
import { QuestDBMCPServer, QuestDBConfig } from 'questdbmcp';
import { z } from 'zod';
const config: QuestDBConfig = {
host: 'localhost',
port: 9000,
};
const server = new QuestDBMCPServer(config, {
setupProcessHandlers: false,
});
// Access the underlying MCP server to register custom tools
server.server.registerTool(
'my-custom-tool',
{
title: 'My Custom Tool',
description: 'A custom tool that uses QuestDB',
inputSchema: {
param: z.string().describe('A parameter'),
},
},
async ({ param }) => {
// Use the QuestDB client
const client = server.questDBClient;
const result = await client.query(`SELECT * FROM my_table WHERE col = '${param}'`);
return {
content: [
{
type: 'text',
text: JSON.stringify(result, null, 2),
},
],
};
}
);
await server.run();
Shutdown
// Gracefully shutdown the server
await server.shutdown();
TypeScript Types
All types are exported and available for use:
import type {
QuestDBConfig,
QueryResult,
QuestDBMCPServerOptions,
} from 'questdbmcp';
Available Tools
1. query
Execute a SQL SELECT query on QuestDB.
Parameters:
query(string, required): The SQL query to execute (SELECT queries only)format(string, optional): Output format -jsonorcsv(default:json)
Example:
{
"query": "SELECT * FROM trades LIMIT 10",
"format": "json"
}
2. insert
Insert data into a QuestDB table. Tables and columns are created automatically if they don't exist.
Parameters:
table(string, required): The name of the table to insert intodata(object, required): An object containing the data to insert- Keys are column names
- Values are the data (strings, numbers, booleans)
- Use
timestampkey for explicit timestamp (milliseconds since epoch) - If
timestampis not provided, the current time is used
Example:
{
"table": "trades",
"data": {
"symbol": "ETH-USD",
"side": "sell",
"price": 2615.54,
"amount": 0.00044,
"timestamp": 1699123456789
}
}
3. list_tables
List all tables in the QuestDB database.
Parameters: None
4. describe_table
Get the schema of a specific table.
Parameters:
table(string, required): The name of the table to describe
Example:
{
"table": "trades"
}
QuestDB Setup
Quick Start with Docker
docker run \
-p 9000:9000 -p 9009:9009 -p 8812:8812 -p 9003:9003 \
questdb/questdb:9.1.1
Quick Start with Homebrew (macOS)
brew install questdb
The QuestDB Web Console will be available at: http://localhost:9000
Development
Building
npm run build
Type Checking
npm run typecheck
Development Mode
npm run dev
Data Types
The insert tool automatically maps JavaScript types to QuestDB types:
- String →
SYMBOL(indexed string type) - Number (integer) →
LONG - Number (float) →
DOUBLE - Boolean →
BOOLEAN - Timestamp →
TIMESTAMP(when using thetimestampfield)
Security Notes
- Only SELECT queries are allowed through the
querytool for safety - The server uses the QuestDB REST API for queries and the InfluxDB Line Protocol for inserts
- Authentication is supported via username/password if your QuestDB instance requires it
Examples
Inserting Trade Data
{
"tool": "insert",
"arguments": {
"table": "trades",
"data": {
"symbol": "BTC-USD",
"side": "buy",
"price": 39269.98,
"amount": 0.001
}
}
}
Querying Data
{
"tool": "query",
"arguments": {
"query": "SELECT symbol, price, amount FROM trades WHERE symbol = 'BTC-USD' ORDER BY timestamp DESC LIMIT 10"
}
}
Listing Tables
{
"tool": "list_tables",
"arguments": {}
}
License
MIT