29b45dd234
- Adds `skills/postgres-best-practices/`: A new skill containing comprehensive Postgres performance optimization rules and guidelines from Supabase. - The skill includes rules for query performance, connection management, security (RLS), and schema design. - Updates `README.md` to include the new skill in the directory.
1.3 KiB
1.3 KiB
title, impact, impactDescription, tags
| title | impact | impactDescription | tags |
|---|---|---|---|
| Set Appropriate Connection Limits | CRITICAL | Prevent database crashes and memory exhaustion | connections, max-connections, limits, stability |
Set Appropriate Connection Limits
Too many connections exhaust memory and degrade performance. Set limits based on available resources.
Incorrect (unlimited or excessive connections):
-- Default max_connections = 100, but often increased blindly
show max_connections; -- 500 (way too high for 4GB RAM)
-- Each connection uses 1-3MB RAM
-- 500 connections * 2MB = 1GB just for connections!
-- Out of memory errors under load
Correct (calculate based on resources):
-- Formula: max_connections = (RAM in MB / 5MB per connection) - reserved
-- For 4GB RAM: (4096 / 5) - 10 = ~800 theoretical max
-- But practically, 100-200 is better for query performance
-- Recommended settings for 4GB RAM
alter system set max_connections = 100;
-- Also set work_mem appropriately
-- work_mem * max_connections should not exceed 25% of RAM
alter system set work_mem = '8MB'; -- 8MB * 100 = 800MB max
Monitor connection usage:
select count(*), state from pg_stat_activity group by state;
Reference: Database Connections