sql-query-mcp 0.3.0

Read-only SQL MCP server for PostgreSQL and MySQL.

sql-query-mcp

中文版

A general-purpose MCP server that lets AI work with multiple databases within clear boundaries.

Current database support

Database	Status	Current availability
PostgreSQL	Supported	Available today
MySQL	Supported	Available today
Hive	Supported	Available today
SQLite	Candidate	Not supported yet
SQL Server	Candidate	Not supported yet
ClickHouse	Candidate	Not supported yet

Product value

sql-query-mcp helps AI clients discover schema, sample data, and analyze read-only queries through one controlled MCP interface.

It keeps connection handling, namespace rules, SQL validation, and audit logging on the server side, so you can expose useful database context to AI without exposing raw connection strings or flattening engine-specific concepts.

What AI can do with it

The current tool set focuses on database discovery, controlled query workflows, asynchronous read-only queries, and one narrow local file import path. You can use it to help an AI assistant understand structure before it generates SQL, runs a bounded query, starts a long-running read-only query, or imports a prepared CSV/XLSX file into an existing table.

MySQL and Hive support explain_query. Hive uses EXPLAIN and EXPLAIN ANALYZE for explain_query.

Tool	PostgreSQL	MySQL	Hive	Purpose
list_connections()	Yes	Yes	Yes	List configured connections
list_schemas(connection_id)	Yes	No	No	List visible PostgreSQL schemas
list_databases(connection_id)	No	Yes	Yes	List visible MySQL or Hive databases
list_tables(connection_id, schema?, database?)	Yes	Yes	Yes	List tables and views
describe_table(connection_id, table_name, schema?, database?)	Yes	Yes	Yes	Inspect columns, keys, and indexes
run_select(connection_id, sql, limit?)	Yes	Yes	Yes	Run short bounded read-only queries
start_query(connection_id, sql, limit?)	Yes	Yes	Yes	Start long-running read-only queries
get_query(query_id, offset?, limit?)	Yes	Yes	Yes	Fetch async query status and paginated results
cancel_query(query_id)	Yes	Yes	Yes	Cancel running async queries
explain_query(connection_id, sql, analyze?)	Yes	Yes	Yes	Inspect query plans
get_table_sample(connection_id, table_name, schema?, database?, limit?)	Yes	Yes	Yes	Fetch small table samples
import_table_file(connection_id, table_name, file_path, schema?, database?, sheet_name?)	Yes	Yes	Yes	Import local CSV/XLSX files

These tools are useful for tasks such as listing namespaces, inspecting table definitions, reviewing indexes, sampling records, running short read-only queries with run_select, running long read-only queries with start_query, get_query, and cancel_query, analyzing read-only queries with EXPLAIN, and importing prepared local files. For full request and response details, see docs/api-reference.md (Chinese).

How boundaries are constrained

The product boundary is intentionally narrow today. PostgreSQL, MySQL, and Hive are available today. Query tools remain read-only, and the only write path is a controlled local CSV/XLSX import into existing tables.

The service keeps those boundaries explicit in a few ways.

• Connections declare engine explicitly, so the server never guesses from connection_id.
• PostgreSQL uses schema, while MySQL and Hive use database, without collapsing both into one vague namespace field.
• Real DSNs stay in environment variables, while config files store only the environment variable names.
• Query execution passes through sqlglot validation before reaching the database. Use run_select for short bounded read-only queries, and use start_query, get_query, and cancel_query for long-running read-only queries.
• The server accepts only SELECT and WITH ... SELECT, rejects comments and multi-statement input, and records audit logs for each call.
• import_table_file doesn't accept raw SQL. It inserts only file columns whose headers exactly match existing table columns.
• Hive import_table_file is intended for small files only and rejects files with more than 1000 data rows. Hive imports write rows one by one, so they can be slow and can hit your MCP client's tool timeout. For bulk Hive loads, use Hive-native LOAD DATA, external tables, or your existing data ingestion pipeline.

For Hive, explain_query uses EXPLAIN and EXPLAIN ANALYZE.

Quick start

sql-query-mcp supports two official PyPI-based setup modes. Both are intended for real usage, not just local testing.

1. Choose how you want your MCP client to start the server.

Use installed command mode if you want a simple local command after one install.

pipx install sql-query-mcp

Use managed launch mode if you want the package source declared directly in your MCP client config.

pipx run --spec sql-query-mcp sql-query-mcp

Pin a version with pipx install 'sql-query-mcp==X.Y.Z' or pipx run --spec 'sql-query-mcp==X.Y.Z' sql-query-mcp. Upgrade installed command mode with pipx upgrade sql-query-mcp.

2. Create a config file.

The server configuration should live outside the repository so the same file works with either startup mode.

mkdir -p ~/.config/sql-query-mcp

Then save the example JSON later in this section as ~/.config/sql-query-mcp/connections.json.

3. Register the server in your MCP client.

• Codex: docs/codex-setup.md (Chinese)
• OpenCode: docs/opencode-setup.md (Chinese)

Installed command mode means your client runs sql-query-mcp directly. Managed launch mode means your client starts the server through pipx run.

In both modes, put SQL_QUERY_MCP_CONFIG and your real database DSNs in the MCP client's environment block instead of exporting them in your shell.

The console entry point is sql-query-mcp, which maps to sql_query_mcp.app:main.

The PyPI install name is sql-query-mcp, and the Python package import path is sql_query_mcp.

For pipx install and pipx run, set SQL_QUERY_MCP_CONFIG explicitly to your config file path. The default config/connections.json path is mainly for source checkouts and local development.

The example config looks like this.

{
  "settings": {
    "default_limit": 200,
    "max_limit": 1000,
    "audit_log_path": "logs/audit.jsonl"
  },
  "connections": [
    {
      "connection_id": "crm_prod_main_ro",
      "engine": "postgres",
      "label": "CRM PostgreSQL production / Main / read-only",
      "env": "prod",
      "tenant": "main",
      "role": "ro",
      "dsn_env": "PG_CONN_CRM_PROD_MAIN_RO",
      "enabled": true,
      "default_schema": "public"
    },
    {
      "connection_id": "crm_mysql_prod_main_ro",
      "engine": "mysql",
      "label": "CRM MySQL production / Main / read-only",
      "env": "prod",
      "tenant": "main",
      "role": "ro",
      "dsn_env": "MYSQL_CONN_CRM_PROD_MAIN_RO",
      "enabled": true,
      "default_database": "crm"
    },
    {
      "connection_id": "warehouse_hive_prod_main_ro",
      "engine": "hive",
      "label": "Warehouse Hive production / Main / read-only",
      "env": "prod",
      "tenant": "main",
      "role": "ro",
      "dsn_env": "HIVE_CONN_WAREHOUSE_PROD_MAIN_RO",
      "enabled": true,
      "default_database": "default"
    }
  ]
}

Set DSNs in the MCP client environment. For Hive, use a Hive DSN such as:

export HIVE_CONN_WAREHOUSE_PROD_MAIN_RO='hive://user:[e-mail]:10000/default?auth=CUSTOM'

Documentation

If you want implementation details, setup guidance, or internal structure, use these docs as your starting points.

• docs/project-overview.md: project goals, concepts, and code structure (Chinese)
• docs/api-reference.md: MCP tool reference (Chinese)
• docs/codex-setup.md: Codex setup steps (Chinese)
• docs/opencode-setup.md: OpenCode setup steps (Chinese)
• docs/release-process.md: PyPI and GitHub Release workflow (Chinese)
• docs/git-workflow.md: repository collaboration workflow (Chinese)

Development

If you want to modify or verify the project locally, use this shortest path. Editable install remains the development path, and the local environment still requires Python 3.10+.

python3.10 -m venv .venv
source .venv/bin/activate
python -m pip install --upgrade pip
pip install -e .
PYTHONPATH=. python3 -m unittest discover -s tests

The main entry point is sql_query_mcp/app.py. Core modules include:

• sql_query_mcp/config.py: config loading and validation
• sql_query_mcp/validator.py: read-only SQL validation
• sql_query_mcp/introspection.py: metadata inspection
• sql_query_mcp/executor.py: query execution and limits
• sql_query_mcp/adapters/: PostgreSQL, MySQL, and Hive adapters

Contributing

If you want to contribute or review the repository workflow, start with these pages.

• CONTRIBUTING.md
• docs/roadmap.md
• docs/git-workflow.md (Chinese)

Run PYTHONPATH=. python3 -m unittest discover -s tests before you submit changes.

License

This project is released under the MIT License. See LICENSE.