Cookbook recipe

Fix “too many clients already”

Applies to PostgreSQL 13–17 Last reviewed May 2026 Grounded in source

What This Is

A production experience capsule based on real incident patterns.

Why It Matters

Builds production judgment under pressure.

Next Step

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Estimated investigation4 min

Scenario

New connections fail with FATAL: sorry, too many clients already. You hit max_connections. Diagnose it See who is connected and what they are doing: SELECT state, count(*) FROM pg_stat_activity GROUP BY state; SELECT pid, state, query_start,…

Investigation Path

New connections fail with FATAL: sorry, too many clients already. You hit max_connections.

Diagnose it

See who is connected and what they are doing:

SELECT state, count(*) FROM pg_stat_activity GROUP BY state;
SELECT pid, state, query_start, left(query,60)
FROM pg_stat_activity WHERE state <> 'idle' ORDER BY query_start;

Why it happens

Every slot up to max_connections is in use — often by idle or idle-in-transaction connections that an app forgot to release, or simply too many direct app connections.

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Career Impact

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