idle_replication_slot_timeout

idle_replication_slot_timeout — Sets the duration a replication slot can remain idle before it is invalidated. Observed in PG18–19 Beta 3; its last measured boot default is 0 s in PG19 Beta 3, with sighup context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA.

Note

Fact — official short description: “Sets the duration a replication slot can remain idle before it is invalidated.”

Identity

Type , Valueinteger: Upstream pg_settings type
Context , Valuesighup: Takes effect after configuration reload
Unit , Values: Raw unit
Range , Value0 – 2147483647: Raw limits in the last observed version
Enum values , Value—: — for non-enum types
Category , ValueReplication / Sending Servers: Upstream classification
Latest boot value , Value0: 0 s

Lifecycle

Fact	Value
First observed	PG18
Present in	PG18–19 Beta 3
Removed in	No
Introduction commit	`ac0e33136abc` — Invalidate inactive replication slots.
Commit date	2025-02-19
Discussion	thread 1 · thread 2

Default history

Measured PG9.0–19 Beta 3 boot defaults
Versions	Raw `boot_val`	Unit	Human value
PG18–19 Beta 3	`0`	`s`	0 s

How it works

Sets the duration a replication slot can remain idle before it is invalidated. A configuration reload applies a new value; existing work already in flight is not retroactively changed.

PostgreSQL 18 measures inactivity from pg_replication_slots.inactive_since and invalidates eligible slots at a checkpoint after the timeout. Zero disables the policy; slots that reserve no WAL and synchronized standby slots are outside this mechanism.

Monitor and change idle_replication_slot_timeout together with max_replication_slots, max_slot_wal_keep_size, primary_slot_name. Validate on the relevant server role and real workload, then use its sighup context to choose session change, reload, or restart; a historical boot default is not the current effective value.

Tuning advice

Tip

Advice. These are workload-specific starting points and must be validated with measurements.

Workload	Guidance
OLTP	Size idle_replication_slot_timeout from topology, failover roles, slot/subscription count, and reconnect headroom. Test worst-case primary latency, standby replay, and disk retention before production.
OLAP	Read standbys and logical subscribers often see long queries or large transactions. Put explicit bounds on replay/apply and monitor lag, worker saturation, slot restart_lsn, and conflict cancellations.
Small nodes	Configure only replication capacity that is actually used. Even a small topology needs bounded timeouts and slot lifecycle; unlimited retention is not reliability.

Pigsty

Values use the fixed 8-vCPU, 32-GiB, 100-GiB SSD fixture and render the current Pigsty templates for PG19 Beta 3; this does not assert current Pigsty support for that historical or beta release.

Template	Effective value	Versus upstream boot	Source expression
OLTP	`7d`	different	`7d`
OLAP	`7d`	different	`7d`
CRIT	`3d`	different	`3d`
TINY	`7d`	different	`7d`

Caution

Advice — pending human review. Fact from the current Pigsty template projection: OLTP: PG18–19 Beta 3 = 7d (dcs); OLAP: PG18–19 Beta 3 = 7d (dcs); CRIT: PG18–19 Beta 3 = 3d (dcs); TINY: PG18–19 Beta 3 = 7d (dcs). Advice, pending human review — Editorial interpretation, pending human maintainer review: the override appears intended to invalidate forgotten PG18 slots, with a stricter window in the CRIT profile; confirm it against the current Pigsty templates, hardware fixture, and operational guarantees before publication.

Common pitfalls

Expecting invalidation exactly when the duration expires rather than at a later checkpoint.
Assuming synchronized standby slots are eligible.
Allowing an automatic invalidation without a subscriber rebootstrap runbook.
Changing it on the wrong primary, standby, sender, or subscriber role.
Watching only configured bytes/time instead of actual lag, slot position, and worker state.

max_replication_slots · max_slot_wal_keep_size · primary_slot_name · wal_keep_size · checkpoint_timeout · max_wal_senders