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.4---5
6# PostgreSQL Read-Only Query Skill
7
8Execute safe, read-only queries against configured PostgreSQL databases.
9
10## Requirements
11
12- Python 3.8+
13- psycopg2-binary: `pip install -r requirements.txt`
14
15## Setup
16
17Create `connections.json` in the skill directory or `~/.config/claude/postgres-connections.json`.
18
19**Security**: Set file permissions to `600` since it contains credentials:
20```bash
21chmod 600 connections.json
22```
23
24```json
25{
26 "databases": [
27 {
28 "name": "production",
29 "description": "Main app database - users, orders, transactions",
30 "host": "db.example.com",
31 "port": 5432,
32 "database": "app_prod",
33 "user": "readonly_user",
34 "password": "your-password",
35 "sslmode": "require"
36 }
37 ]
38}
39```
40
41### Config Fields
42
43| Field | Required | Description |
44|-------|----------|-------------|
45| name | Yes | Identifier for the database (case-insensitive) |
46| description | Yes | What data this database contains (used for auto-selection) |
47| host | Yes | Database hostname |
48| port | No | Port number (default: 5432) |
49| database | Yes | Database name |
50| user | Yes | Username |
51| password | Yes | Password |
52| sslmode | No | SSL mode: disable, allow, prefer (default), require, verify-ca, verify-full |
53
54## Usage
55
56### List configured databases
57```bash
58python3 scripts/query.py --list
59```
60
61### Query a database
62```bash
63python3 scripts/query.py --db production --query "SELECT * FROM users LIMIT 10"
64```
65
66### List tables
67```bash
68python3 scripts/query.py --db production --tables
69```
70
71### Show schema
72```bash
73python3 scripts/query.py --db production --schema
74```
75
76### Limit results
77```bash
78python3 scripts/query.py --db production --query "SELECT * FROM orders" --limit 100
79```
80
81## Database Selection
82
83Match user intent to database `description`:
84
85| User asks about | Look for description containing |
86|-----------------|--------------------------------|
87| users, accounts | users, accounts, customers |
88| orders, sales | orders, transactions, sales |
89| analytics, metrics | analytics, metrics, reports |
90| logs, events | logs, events, audit |
91
92If unclear, run `--list` and ask user which database.
93
94## Safety Features
95
96- **Read-only session**: Connection uses PostgreSQL `readonly=True` mode (primary protection)
97- **Query validation**: Only SELECT, SHOW, EXPLAIN, WITH queries allowed
98- **Single statement**: Multiple statements per query rejected
99- **SSL support**: Configurable SSL mode for encrypted connections
100- **Query timeout**: 30-second statement timeout enforced
101- **Memory protection**: Max 10,000 rows per query to prevent OOM
102- **Column width cap**: 100 char max per column for readable output
103- **Credential sanitization**: Error messages don't leak passwords
104
105## Troubleshooting
106
107| Error | Solution |
108|-------|----------|
109| Config not found | Create `connections.json` in skill directory |
110| Authentication failed | Check username/password in config |
111| Connection timeout | Verify host/port, check firewall/VPN |
112| SSL error | Try `"sslmode": "disable"` for local databases |
113| Permission warning | Run `chmod 600 connections.json` |
114
115## Exit Codes
116
117- **0**: Success
118- **1**: Error (config missing, auth failed, invalid query, database error)
119
120## Workflow
121
1221. Run `--list` to show available databases
1232. Match user intent to database description
1243. Run `--tables` or `--schema` to explore structure
1254. Execute query with appropriate LIMIT
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