Cookbook recipe

Avoid idle-in-transaction bloat

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.

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Estimated investigation4 min

Scenario

An app opens a transaction, does one query, then sits idle while holding it open. This pins the vacuum horizon and causes bloat. Diagnose it Find idle-in-transaction sessions and their age: SELECT pid, now()-xact_start AS xact_age,…

Investigation Path

An app opens a transaction, does one query, then sits idle while holding it open. This pins the vacuum horizon and causes bloat.

Diagnose it

Find idle-in-transaction sessions and their age:

SELECT pid, now()-xact_start AS xact_age, state, left(query,60)
FROM pg_stat_activity
WHERE state = 'idle in transaction'
ORDER BY xact_age DESC;

Why it happens

An open transaction holds back xmin — VACUUM cannot remove dead tuples newer than the oldest running transaction. A long idle-in-transaction session therefore blocks cleanup cluster-wide and bloats tables.

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Related & next steps

More like this

Lock Monitoring Gaps: Deadlocks Not Logged Autovacuum Killing Performance (I/O Spikes) Deadlock rate spiking — finding and eliminating the cause Hot Standby and Recovery Conflicts Logical replication: publication and subscription setup

Concepts on this page

xmin horizon (OldestXmin) Transaction Dead tuple VACUUM Bloat
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