How do I install the Postgres Query skill?

Run npx skillmds@latest add majiayu000/postgres-query in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

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Which AI agents work with Postgres Query?

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Is Postgres Query free to use?

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Who published Postgres Query?

majiayu000 (@majiayu000) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Postgres Query by majiayu000 — Agent Skill

Name: Postgres Query
Rating: 4.5 (4 reviews)
Author: majiayu000

Postgres Query

Run PostgreSQL queries for testing, debugging, and performance analysis. Use when you need to query the database directly, run EXPLAIN ANALYZE, compare query results, or test SQL optimizations. Always uses read-only connections unless explicitly directed otherwise.

majiayu000 Updated Sep 9, 2026 567 repo stars

File contents

PostgreSQL Query Testing

Use this skill to run ad-hoc PostgreSQL queries for testing, debugging, and performance analysis.

Running Queries

Use the included query script:

node .claude/skills/postgres-query/query.mjs "SELECT * FROM \"User\" LIMIT 5"

Options

Flag	Description
`--explain`	Run EXPLAIN ANALYZE on the query
`--writable`	Use primary database instead of read replica (requires user permission)
`--timeout <s>`, `-t`	Query timeout in seconds (default: 30)
`--file`, `-f`	Read query from a file
`--json`	Output results as JSON
`--quiet`, `-q`	Minimal output, only results

Examples

# Simple query
node .claude/skills/postgres-query/query.mjs "SELECT id, username FROM \"User\" LIMIT 5"

# Check query performance
node .claude/skills/postgres-query/query.mjs --explain "SELECT * FROM \"Model\" WHERE id = 1"

# Override default 30s timeout for longer queries
node .claude/skills/postgres-query/query.mjs --timeout 60 "SELECT ... (complex query)"

# Query from file
node .claude/skills/postgres-query/query.mjs -f my-query.sql

# JSON output for processing
node .claude/skills/postgres-query/query.mjs --json "SELECT id, username FROM \"User\" LIMIT 3"

Safety Features

Read-only by default: Uses DATABASE_REPLICA_URL to prevent accidental writes
Write protection: Blocks INSERT/UPDATE/DELETE/DROP unless --writable flag is used
Explicit permission required: Before using --writable, you MUST ask the user for permission

When to Use --writable

Only use the --writable flag when:

The user explicitly requests write access
You need to test write operations
You're verifying transaction behavior

IMPORTANT: Always ask the user for permission before running with --writable.

Comparing Query Performance

To compare two query approaches:

# Run first approach
node .claude/skills/postgres-query/query.mjs --explain "SELECT ... (approach 1)"

# Run second approach
node .claude/skills/postgres-query/query.mjs --explain "SELECT ... (approach 2)"

# Compare actual results
node .claude/skills/postgres-query/query.mjs --json "SELECT ... (approach 1)" > /tmp/q1.json
node .claude/skills/postgres-query/query.mjs --json "SELECT ... (approach 2)" > /tmp/q2.json

Verifying Index Usage

Run with --explain and look for:

Good: "Index Scan", "Bitmap Index Scan", "Index Only Scan"
Bad: "Seq Scan" on large tables (indicates missing or unused index)

node .claude/skills/postgres-query/query.mjs --explain "SELECT * FROM \"Account\" WHERE provider = 'discord'"

---name: postgres-querydescription: Run PostgreSQL queries for testing, debugging, and performance analysis. Use when you need to query the database directly, run EXPLAIN ANALYZE, compare query results, or test SQL optimizations. Always uses read-only connections unless explicitly directed otherwise.--- # PostgreSQL Query Testing Use this skill to run ad-hoc PostgreSQL queries for testing, debugging, and performance analysis. ## Running Queries Use the included query script: ```bash node .claude/skills/postgres-query/query.mjs "SELECT * FROM \"User\" LIMIT 5" ``` ### Options | Flag | Description | |------|-------------| | `--explain` | Run EXPLAIN ANALYZE on the query | | `--writable` | Use primary database instead of read replica (requires user permission) | | `--timeout <s>`, `-t` | Query timeout in seconds (default: 30) | | `--file`, `-f` | Read query from a file | | `--json` | Output results as JSON | | `--quiet`, `-q` | Minimal output, only results | ### Examples ```bash # Simple query node .claude/skills/postgres-query/query.mjs "SELECT id, username FROM \"User\" LIMIT 5" # Check query performance node .claude/skills/postgres-query/query.mjs --explain "SELECT * FROM \"Model\" WHERE id = 1" # Override default 30s timeout for longer queries node .claude/skills/postgres-query/query.mjs --timeout 60 "SELECT ... (complex query)" # Query from file node .claude/skills/postgres-query/query.mjs -f my-query.sql # JSON output for processing node .claude/skills/postgres-query/query.mjs --json "SELECT id, username FROM \"User\" LIMIT 3" ``` ## Safety Features 1. **Read-only by default**: Uses `DATABASE_REPLICA_URL` to prevent accidental writes 2. **Write protection**: Blocks INSERT/UPDATE/DELETE/DROP unless `--writable` flag is used 3. **Explicit permission required**: Before using `--writable`, you MUST ask the user for permission ## When to Use --writable Only use the `--writable` flag when: - The user explicitly requests write access - You need to test write operations - You're verifying transaction behavior **IMPORTANT**: Always ask the user for permission before running with `--writable`. ## Comparing Query Performance To compare two query approaches: ```bash # Run first approach node .claude/skills/postgres-query/query.mjs --explain "SELECT ... (approach 1)" # Run second approach node .claude/skills/postgres-query/query.mjs --explain "SELECT ... (approach 2)" # Compare actual results node .claude/skills/postgres-query/query.mjs --json "SELECT ... (approach 1)" > /tmp/q1.json node .claude/skills/postgres-query/query.mjs --json "SELECT ... (approach 2)" > /tmp/q2.json ``` ## Verifying Index Usage Run with `--explain` and look for: - **Good**: "Index Scan", "Bitmap Index Scan", "Index Only Scan" - **Bad**: "Seq Scan" on large tables (indicates missing or unused index) ```bash node .claude/skills/postgres-query/query.mjs --explain "SELECT * FROM \"Account\" WHERE provider = 'discord'" ```

Frequently asked questions