log_replication_commands

log_replication_commands is the PostgreSQL setting that controls whether PostgreSQL logs each replication command.

Note

Fact — official short description: “Logs each replication command.”

Identity

Type , Valuebool: Upstream pg_settings type
Context , Valuesuperuser: Settable at runtime by a superuser
Unit , Value—: Raw unit
Range , Value—: Raw limits in the last observed version
Enum values , Value—: — for non-enum types
Category , ValueReporting and Logging / What to Log: 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	`4ad2a548050f` — Add GUC to enable logging of replication commands.
Commit date	2014-09-13
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

log_replication_commands logs each replication command. It covers replication-protocol commands as well as SQL replication commands and can therefore expose replication topology and slot activity.

log_replication_commands is a SUPERUSER-context setting. Superuser or a role granted the appropriate SET privilege can change it for a session, while ALTER ROLE or ALTER DATABASE can establish a default for future sessions.

It changes emitted diagnostic data rather than query semantics, but volume, sensitive content, log_line_prefix, destinations, collector throughput, and retention determine operational cost and usefulness.

Tuning advice

Tip

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

Workload	Guidance
OLTP	Tune log_replication_commands against an explicit observability question and a measured log-volume budget. Prefer selective thresholds, sampling, or role-level overrides over indiscriminate capture.
OLAP	Analytical jobs can justify richer log_replication_commands telemetry, but account for long statements, large bind values, and bursty completion patterns in the log pipeline.
Small nodes	Keep log_replication_commands useful but bounded: verify disk, collector, retention, and redaction capacity before increasing detail or frequency.

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 inference: Replication command history supports diagnosing slots, senders, failover, and topology changes across managed clusters.

Common pitfalls

Changing log_replication_commands in one session and assuming role defaults, database defaults, or other pooled sessions changed with it.
Enabling richer logging without budgeting collector throughput, storage, retention, and downstream query cost.
Writing SQL text, bind values, identities, or host data without a redaction and access-control policy.
Changing log_replication_commands globally without a rollback plan and a client or operational compatibility test.

log_checkpoints · log_autovacuum_min_duration · log_lock_waits · log_lock_failures · log_temp_files