Database New Added 28 August 2026

PostgreSQL: canceling statement due to statement timeout

The query ran longer than statement_timeout and was cancelled by the server. This is a guardrail doing its job. The interesting question is why the query is slow, not how to raise the limit.

Quick fix

Read the commands before running them. Anything that restarts a service, deletes data or changes permissions should be tried on a non-production system first.

Quick fix

-- What is the limit, and at which level is it set?
SHOW statement_timeout;
SELECT rolname, rolconfig FROM pg_roles WHERE rolname = current_user;

-- Find the plan
EXPLAIN (ANALYZE, BUFFERS) SELECT ...;

-- Raise it only for one known-long statement
SET LOCAL statement_timeout = '5min';

-- Usually the real fix is an index or a smaller batch
CREATE INDEX CONCURRENTLY idx_events_created ON events (created_at);

How to diagnose Database errors

Database errors group into connection exhaustion, lock contention and deadlocks, constraint violations, and resource limits. Connection errors under load are the most misdiagnosed: "too many connections" is almost never fixed by raising max_connections, because each connection costs memory. It is fixed by putting a pooler in front and finding the code path that leaks connections.

If the quick fix above does not resolve it, work through these steps. They apply to this whole class of error, not just to this one message, which is usually what saves the time.

Look at what the server currently sees: SELECT * FROM pg_stat_activity in PostgreSQL, SHOW FULL PROCESSLIST in MySQL. Sessions sitting in idle in transaction are the usual culprit behind connection exhaustion.
For deadlocks, read the deadlock report the database logs. It names both transactions and the exact lock order. The fix is nearly always to make all code paths acquire locks in the same order.
Check whether the error is from the database or from a pooler. PgBouncer, ProxySQL and RDS Proxy return their own errors that look database-native but need pooler-side fixes.
Run EXPLAIN (ANALYZE, BUFFERS) on slow queries. Lock-wait timeouts are often just very slow queries holding locks longer than they should.
Verify you are connected to the writer, not a read replica. READONLY and "cannot execute in a read-only transaction" errors mean traffic is reaching the wrong endpoint.

Tools worth reaching for

pg_stat_activity
SHOW ENGINE INNODB STATUS
EXPLAIN ANALYZE
slow query log
pgbadger

Authoritative references

Primary documentation for this error, worth reading before applying any fix in production.

postgresql.org

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