# Rules

> Guides configuring connection pooling for Postgres to prevent connection exhaustion under load.

- Skill: `jorcan/rules` (Agent Skill, multi-file: 3 files)
- Install (CLI): `npx skillmds@latest add jorcan/rules`
- Raw SKILL.md: https://api.skillmd.com/api/skills/jorcan/rules/raw
- Safety review: PASS (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Data & Analytics, Coding & Dev Tools, SQL & Databases
- Tags: Connection Pooling, Database Performance, Pgbouncer, Postgres
- Author: jorcan (https://skillmd.com/u/jorcan)
- Updated: 2026-08-22
- Page: https://skillmd.com/skills/jorcan/rules

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## Use Connection Pooling for All Applications

Postgres connections are expensive (1-3MB RAM each). Without pooling, applications exhaust connections under load.

**Incorrect (new connection per request):**

```sql
-- Each request creates a new connection
-- Application code: db.connect() per request
-- Result: 500 concurrent users = 500 connections = crashed database

-- Check current connections
select count(*) from pg_stat_activity;  -- 487 connections!
```

**Correct (connection pooling):**

```sql
-- Use a pooler like PgBouncer between app and database
-- Application connects to pooler, pooler reuses a small pool to Postgres

-- Configure pool_size based on: (CPU cores * 2) + spindle_count
-- Example for 4 cores: pool_size = 10

-- Result: 500 concurrent users share 10 actual connections
select count(*) from pg_stat_activity;  -- 10 connections
```

Pool modes:

- **Transaction mode**: connection returned after each transaction (best for most apps)
- **Session mode**: connection held for entire session (needed for prepared statements, temp tables)

Reference: [Connection Pooling](https://supabase.com/docs/guides/database/connecting-to-postgres#connection-pooler)