1---
2title: Set Appropriate Connection Limits
3impact: CRITICAL
4impactDescription: Prevent database crashes and memory exhaustion
5tags: connections, max-connections, limits, stability
6---
7 
8## Set Appropriate Connection Limits
9 
10Too many connections exhaust memory and degrade performance. Set limits based on available resources.
11 
12**Incorrect (unlimited or excessive connections):**
13 
14```sql
15-- Default max_connections = 100, but often increased blindly
16show max_connections;  -- 500 (way too high for 4GB RAM)
17 
18-- Each connection uses 1-3MB RAM
19-- 500 connections * 2MB = 1GB just for connections!
20-- Out of memory errors under load
21```
22 
23**Correct (calculate based on resources):**
24 
25```sql
26-- Formula: max_connections = (RAM in MB / 5MB per connection) - reserved
27-- For 4GB RAM: (4096 / 5) - 10 = ~800 theoretical max
28-- But practically, 100-200 is better for query performance
29 
30-- Recommended settings for 4GB RAM
31alter system set max_connections = 100;
32 
33-- Also set work_mem appropriately
34-- work_mem * max_connections should not exceed 25% of RAM
35alter system set work_mem = '8MB';  -- 8MB * 100 = 800MB max
36```
37 
38Monitor connection usage:
39 
40```sql
41select count(*), state from pg_stat_activity group by state;
42```
43 
44Reference: [Database Connections](https://supabase.com/docs/guides/platform/performance#connection-management)
45