JaviMaligno/postgres_mcp

CI PyPI version npm version License: MIT

MCP server for PostgreSQL database operations. Works with Claude Code, Claude Desktop, Cursor, and any MCP-compatible client.

Language Versions

This repository contains both TypeScript and Python implementations:

Version	Directory	Status	Installation
TypeScript	/typescript	✅ Recommended (Smithery)	npm install -g postgresql-mcp
Python	/python	✅ Stable	pipx install postgresql-mcp

Note: The TypeScript version is used for Smithery deployments. Both versions provide identical functionality.

Features

• Query Execution: Execute SQL queries with read-only protection by default
• Schema Exploration: List schemas, tables, views, and functions
• Table Analysis: Describe structure, indexes, constraints, and statistics
• Performance Tools: EXPLAIN queries and analyze table health
• Security First: SQL injection prevention, credential protection, read-only by default
• MCP Prompts: Guided workflows for exploration, query building, and documentation
• MCP Resources: Browsable database structure as markdown

Quick Start

TypeScript (Recommended for Smithery)

# Install globally
npm install -g postgresql-mcp

# Or run directly with npx
npx postgresql-mcp

Python

# Install
pipx install postgresql-mcp

# Configure Claude Code
claude mcp add postgres -s user \
  -e POSTGRES_HOST=localhost \
  -e POSTGRES_USER=your_user \
  -e POSTGRES_PASSWORD=your_password \
  -e POSTGRES_DB=your_database \
  -- postgresql-mcp

Full Installation Guide - Includes database permissions setup, remote connections, and troubleshooting.

Configuration

Environment Variables

Variable	Required	Default	Description
POSTGRES_HOST		localhost	Database host
POSTGRES_PORT		5432	Database port
POSTGRES_USER	✅		Database user
POSTGRES_PASSWORD	✅		Database password
POSTGRES_DB	✅		Database name
POSTGRES_SSLMODE		prefer	SSL mode
ALLOW_WRITE_OPERATIONS		false	Enable INSERT/UPDATE/DELETE
QUERY_TIMEOUT		30	Query timeout (seconds)
MAX_ROWS		1000	Maximum rows returned

Claude Code CLI

# TypeScript version
claude mcp add postgres -s user \
  -e POSTGRES_HOST=localhost \
  -e POSTGRES_USER=your_user \
  -e POSTGRES_PASSWORD=your_password \
  -e POSTGRES_DB=your_database \
  -- npx postgresql-mcp

# Python version
claude mcp add postgres -s user \
  -e POSTGRES_HOST=localhost \
  -e POSTGRES_USER=your_user \
  -e POSTGRES_PASSWORD=your_password \
  -e POSTGRES_DB=your_database \
  -- postgresql-mcp

Cursor IDE

Add to ~/.cursor/mcp.json:

{
  "mcpServers": {
    "postgres": {
      "command": "npx",
      "args": ["postgresql-mcp"],
      "env": {
        "POSTGRES_HOST": "localhost",
        "POSTGRES_PORT": "5432",
        "POSTGRES_USER": "your_user",
        "POSTGRES_PASSWORD": "your_password",
        "POSTGRES_DB": "your_database"
      }
    }
  }
}

Available Tools (14 total)

Query Execution

Tool	Description
query	Execute read-only SQL queries against the database
execute	Execute write operations (INSERT/UPDATE/DELETE) when enabled
explain_query	Get EXPLAIN plan for query optimization

Schema Exploration

Tool	Description
list_schemas	List all schemas in the database
list_tables	List tables in a specific schema
describe_table	Get table structure (columns, types, constraints)
list_views	List views in a schema
describe_view	Get view definition and columns
list_functions	List functions and procedures

Performance & Analysis

Tool	Description
table_stats	Get table statistics (row count, size, bloat)
list_indexes	List indexes for a table
list_constraints	List constraints (PK, FK, UNIQUE, CHECK)

Database Info

Tool	Description
get_database_info	Get database version and connection info
search_columns	Search for columns by name across all tables

MCP Prompts

Guided workflows that help Claude assist you effectively:

Prompt	Description
explore_database	Comprehensive database exploration and overview
query_builder	Help building efficient queries for a table
performance_analysis	Analyze table performance and suggest optimizations
data_dictionary	Generate documentation for a schema

MCP Resources

Browsable database structure:

Resource URI	Description
postgres://schemas	List all schemas
postgres://schemas/{schema}/tables	Tables in a schema
postgres://schemas/{schema}/tables/{table}	Table details
postgres://database	Database connection info

Example Usage

Once configured, ask Claude to:

Schema Exploration:

• "List all tables in the public schema"
• "Describe the users table structure"
• "What views are available?"

Querying:

• "Show me 10 rows from the orders table"
• "Find all customers who placed orders last week"
• "Count records grouped by status"

Performance Analysis:

• "What indexes exist on the orders table?"
• "Analyze the performance of the users table"
• "Explain this query: SELECT * FROM orders WHERE created_at > '2024-01-01'"

Documentation:

• "Generate a data dictionary for this database"
• "What columns contain 'email' in their name?"

Security

This MCP server implements multiple security layers:

Read-Only by Default

Write operations (INSERT, UPDATE, DELETE) are blocked unless explicitly enabled via ALLOW_WRITE_OPERATIONS=true.

SQL Injection Prevention

• All queries are validated before execution
• Dangerous operations (DROP DATABASE, etc.) are always blocked
• Multiple statements are not allowed
• SQL comments are blocked

Credential Protection

• Passwords stored using secure string types
• Credentials never appear in logs or error messages

Query Limits

• Results limited by MAX_ROWS (default: 1000)
• Query timeout configurable via QUERY_TIMEOUT

Development

TypeScript

cd typescript
npm install
npm run build
npm run dev  # Watch mode

Python

cd python
uv sync
uv run pytest -v --cov=postgres_mcp

Running Tests

# Python unit tests (no database required)
cd python
uv run pytest tests/test_security.py tests/test_settings.py -v

# Integration tests (requires PostgreSQL)
docker-compose up -d
uv run pytest tests/test_integration.py -v

Troubleshooting

Connection Issues

# Verify PostgreSQL is running
pg_isready -h localhost -p 5432

# Test connection with psql
psql -h localhost -U your_user -d your_database

Permission Denied

Ensure your database user has SELECT permissions:

GRANT SELECT ON ALL TABLES IN SCHEMA public TO your_user;

MCP Server Not Connecting

# Check server status
claude mcp get postgres

# Test server directly
postgresql-mcp  # Should wait for MCP messages

Links

• PyPI Package
• npm Package
• Installation Guide
• GitHub Repository

Author

Built by Javier Aguilar - AI Agent Architect specializing in multi-agent orchestration and MCP development.

License

MIT