Cookbook recipe

Stop transaction ID wraparound before it stops you

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

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A production experience capsule based on real incident patterns.

Why It Matters

Builds production judgment under pressure.

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Estimated investigation4 min

Scenario

You see warnings about transaction ID wraparound or "database is not accepting commands". This is an emergency — act before the database shuts down to protect itself. Diagnose it Find the databases/tables closest to wraparound: SELECT…

Investigation Path

You see warnings about transaction ID wraparound or “database is not accepting commands”. This is an emergency — act before the database shuts down to protect itself.

Diagnose it

Find the databases/tables closest to wraparound:

SELECT datname, age(datfrozenxid) AS xid_age
FROM pg_database ORDER BY xid_age DESC;

SELECT relname, age(relfrozenxid) AS xid_age
FROM pg_class WHERE relkind='r'
ORDER BY xid_age DESC LIMIT 20;

Why it happens

XIDs are 32-bit and wrap around. VACUUM “freezes” old rows so their XIDs can be reused. If vacuum falls behind autovacuum_freeze_max_age, age climbs toward 2 billion and PostgreSQL stops accepting writes to prevent data loss.

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Related & next steps

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Concepts on this page

Transaction ID wraparound Transaction Autovacuum VACUUM
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