PostgreSQL Multi-Schema MCP Server

PostgreSQL Multi-Schema MCP Server

A Model Context Protocol server that provides read-only access to PostgreSQL databases with enhanced multi-schema support. This server enables LLMs to inspect database schemas across multiple namespaces and execute read-only queries while maintaining schema isolation.

Key Features

• Multi-Schema Support: Explicitly specify which schemas to expose through command-line configuration
• Schema Isolation: Strict access control to only authorized schemas listed during server startup
• Cross-Schema Discovery: Unified view of tables across multiple schemas while maintaining schema boundaries
• Metadata Security: Filters system catalogs to only expose user-defined tables in specified schemas

Components

Tools

• query
  • Execute read-only SQL queries against the connected database
  • Input: sql (string): The SQL query to execute
  • All queries are executed within a READ ONLY transaction
  • Schema context maintained through search_path restriction

Resources

The server provides schema information for each table across authorized schemas:

• Table Schemas (postgres://<host>/<db_schema>/<table>/schema)
  • JSON schema information for each table
  • Includes column names, data types, and type modifiers
  • Automatically discovered from database metadata
  • Multi-schema support with explicit schema allow-list

Usage

The server requires a database URL and accepts a comma-separated list of schemas to expose:

npx -y mcp-server-postgres-multi-schema <database-url> [schemas]

• database-url: PostgreSQL connection string (e.g., postgresql://localhost/mydb)
• schemas: Comma-separated list of schemas to expose (defaults to 'public' if not specified)

Examples

# Connect with default public schema
npx -y mcp-server-postgres-multi-schema postgresql://localhost/mydb

# Connect with multiple schemas
npx -y mcp-server-postgres-multi-schema postgresql://localhost/mydb public,analytics,staging

Usage with Claude Desktop

Configure the "mcpServers" section in your claude_desktop_config.json:

NPX

{
  "mcpServers": {
    "postgres": {
      "command": "npx",
      "args": [
        "-y",
        "mcp-server-postgres-multi-schema",
        "postgresql://localhost/mydb",
        "public,audit"
      ]
    }
  }
}

License

This multi-schema MCP server is licensed under the MIT License. You may use, modify, and distribute the software according to the terms in the LICENSE file.