PostgreSQL Read-Only Query Skill
Execute safe, read-only queries against configured PostgreSQL databases.
Requirements
- Python 3.8+
- psycopg2-binary:
pip install -r requirements.txt
Setup
Create connections.json in the skill directory or ~/.config/claude/postgres-connections.json.
Security: Set file permissions to 600 since it contains credentials:
chmod 600 connections.json
{
"databases": [
{
"name": "production",
"description": "Main app database - users, orders, transactions",
"host": "db.example.com",
"port": 5432,
"database": "app_prod",
"user": "readonly_user",
"password": "your-password",
"sslmode": "require"
}
]
}
Config Fields
| Field |
Required |
Description |
| name |
Yes |
Identifier for the database (case-insensitive) |
| description |
Yes |
What data this database contains (used for auto-selection) |
| host |
Yes |
Database hostname |
| port |
No |
Port number (default: 5432) |
| database |
Yes |
Database name |
| user |
Yes |
Username |
| password |
Yes |
Password |
| sslmode |
No |
SSL mode: disable, allow, prefer (default), require, verify-ca, verify-full |
Usage
List configured databases
python3 scripts/query.py --list
Query a database
python3 scripts/query.py --db production --query "SELECT * FROM users LIMIT 10"
List tables
python3 scripts/query.py --db production --tables
Show schema
python3 scripts/query.py --db production --schema
Limit results
python3 scripts/query.py --db production --query "SELECT * FROM orders" --limit 100
Database Selection
Match user intent to database description:
| User asks about |
Look for description containing |
| users, accounts |
users, accounts, customers |
| orders, sales |
orders, transactions, sales |
| analytics, metrics |
analytics, metrics, reports |
| logs, events |
logs, events, audit |
If unclear, run --list and ask user which database.
Safety Features
- Read-only session: Connection uses PostgreSQL
readonly=True mode (primary protection)
- Query validation: Only SELECT, SHOW, EXPLAIN, WITH queries allowed
- Single statement: Multiple statements per query rejected
- SSL support: Configurable SSL mode for encrypted connections
- Query timeout: 30-second statement timeout enforced
- Memory protection: Max 10,000 rows per query to prevent OOM
- Column width cap: 100 char max per column for readable output
- Credential sanitization: Error messages don't leak passwords
Troubleshooting
| Error |
Solution |
| Config not found |
Create connections.json in skill directory |
| Authentication failed |
Check username/password in config |
| Connection timeout |
Verify host/port, check firewall/VPN |
| SSL error |
Try "sslmode": "disable" for local databases |
| Permission warning |
Run chmod 600 connections.json |
Exit Codes
- 0: Success
- 1: Error (config missing, auth failed, invalid query, database error)
Workflow
- Run
--list to show available databases
- Match user intent to database description
- Run
--tables or --schema to explore structure
- Execute query with appropriate LIMIT
1---2name: postgres3description: Execute read-only SQL queries against multiple PostgreSQL databases. Use when: (1) querying PostgreSQL databases, (2) exploring database schemas/tables, (3) running SELECT queries for data analysis, (4) checking database contents. Supports multiple database connections with descriptions for intelligent auto-selection. Blocks all write operations (INSERT, UPDATE, DELETE, DROP, etc.) for safety.4license: Apache-2.05---67# PostgreSQL Read-Only Query Skill89Execute safe, read-only queries against configured PostgreSQL databases.1011## Requirements1213- Python 3.8+14- psycopg2-binary: `pip install -r requirements.txt`1516## Setup1718Create `connections.json` in the skill directory or `~/.config/claude/postgres-connections.json`.1920**Security**: Set file permissions to `600` since it contains credentials:21```bash22chmod 600 connections.json23```2425```json26{27 "databases": [28 {29 "name": "production",30 "description": "Main app database - users, orders, transactions",31 "host": "db.example.com",32 "port": 5432,33 "database": "app_prod",34 "user": "readonly_user",35 "password": "your-password",36 "sslmode": "require"37 }38 ]39}40```4142### Config Fields4344| Field | Required | Description |45|-------|----------|-------------|46| name | Yes | Identifier for the database (case-insensitive) |47| description | Yes | What data this database contains (used for auto-selection) |48| host | Yes | Database hostname |49| port | No | Port number (default: 5432) |50| database | Yes | Database name |51| user | Yes | Username |52| password | Yes | Password |53| sslmode | No | SSL mode: disable, allow, prefer (default), require, verify-ca, verify-full |5455## Usage5657### List configured databases58```bash59python3 scripts/query.py --list60```6162### Query a database63```bash64python3 scripts/query.py --db production --query "SELECT * FROM users LIMIT 10"65```6667### List tables68```bash69python3 scripts/query.py --db production --tables70```7172### Show schema73```bash74python3 scripts/query.py --db production --schema75```7677### Limit results78```bash79python3 scripts/query.py --db production --query "SELECT * FROM orders" --limit 10080```8182## Database Selection8384Match user intent to database `description`:8586| User asks about | Look for description containing |87|-----------------|--------------------------------|88| users, accounts | users, accounts, customers |89| orders, sales | orders, transactions, sales |90| analytics, metrics | analytics, metrics, reports |91| logs, events | logs, events, audit |9293If unclear, run `--list` and ask user which database.9495## Safety Features9697- **Read-only session**: Connection uses PostgreSQL `readonly=True` mode (primary protection)98- **Query validation**: Only SELECT, SHOW, EXPLAIN, WITH queries allowed99- **Single statement**: Multiple statements per query rejected100- **SSL support**: Configurable SSL mode for encrypted connections101- **Query timeout**: 30-second statement timeout enforced102- **Memory protection**: Max 10,000 rows per query to prevent OOM103- **Column width cap**: 100 char max per column for readable output104- **Credential sanitization**: Error messages don't leak passwords105106## Troubleshooting107108| Error | Solution |109|-------|----------|110| Config not found | Create `connections.json` in skill directory |111| Authentication failed | Check username/password in config |112| Connection timeout | Verify host/port, check firewall/VPN |113| SSL error | Try `"sslmode": "disable"` for local databases |114| Permission warning | Run `chmod 600 connections.json` |115116## Exit Codes117118- **0**: Success119- **1**: Error (config missing, auth failed, invalid query, database error)120121## Workflow1221231. Run `--list` to show available databases1242. Match user intent to database description1253. Run `--tables` or `--schema` to explore structure1264. Execute query with appropriate LIMIT
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