track_commit_timestamp

track_commit_timestamp — Collects transaction commit time. Observed in PG9.5–19 Beta 3; its last measured boot default is off in PG19 Beta 3, with postmaster context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA.

Note

Fact — official short description: “Collects transaction commit time.”

Identity

Type , Valuebool: Upstream pg_settings type
Context , Valuepostmaster: Requires a server restart
Unit , Value—: Raw unit
Range , Value—: Raw limits in the last observed version
Enum values , Value—: — for non-enum types
Category , ValueReplication / Sending Servers: Upstream classification
Latest boot value , Valueoff: off

Lifecycle

Fact	Value
First observed	PG9.5
Present in	PG9.5–19 Beta 3
Removed in	No
Introduction commit	`73c986adde5d` — Keep track of transaction commit timestamps
Commit date	2014-12-03
Discussion	—

Default history

Measured PG9.0–19 Beta 3 boot defaults
Versions	Raw `boot_val`	Unit	Human value
PG9.5–19 Beta 3	`off`	—	off

How it works

Collects transaction commit time. The value is fixed when the server starts, so changing it requires a restart.

PostgreSQL stores transaction commit timestamps in an auxiliary SLRU so SQL and replication-origin features can query them later. It must be enabled at startup before the history is collected and adds storage/I/O overhead; it cannot reconstruct older timestamps.

Monitor and change track_commit_timestamp together with max_active_replication_origins, max_logical_replication_workers, max_replication_slots. Validate on the relevant server role and real workload, then use its postmaster 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 track_commit_timestamp 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	`on`	different	`'on'`
OLAP	`on`	different	`'on'`
CRIT	`on`	different	`'on'`
TINY	`on`	different	`'on'`

Caution

Advice — pending human review. Fact from the current Pigsty template projection: OLTP: PG9.5–19 Beta 3 = on (dcs); OLAP: PG9.5–19 Beta 3 = on (dcs); CRIT: PG9.5–19 Beta 3 = on (dcs); TINY: PG9.5–19 Beta 3 = on (dcs). Advice, pending human review — Editorial interpretation, pending human maintainer review: the override appears intended to make commit-time metadata available for diagnostics and replication workflows; confirm it against the current Pigsty templates, hardware fixture, and operational guarantees before publication.

Common pitfalls

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.
Failing over to a node that lacks the old primary’s capacity or prerequisites.
Using infinite waits or WAL retention to hide a failed consumer.

max_active_replication_origins · max_logical_replication_workers · max_replication_slots · idle_replication_slot_timeout · max_slot_wal_keep_size · max_wal_senders