log_lock_waits

log_lock_waits is the PostgreSQL setting that controls whether PostgreSQL logs long lock waits.

Note

Fact — official short description: “Logs long lock waits.”

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 , Valueon: on

Lifecycle

Fact	Value
First observed	PG9.0 (research boundary)
Present in	PG9.0–19 Beta 3
Removed in	No
Introduction commit	Not asserted: predates the PG9.0 research boundary
Commit date	—
Discussion	—

Default history

Measured PG9.0–19 Beta 3 boot defaults
Versions	Raw `boot_val`	Unit	Human value
PG9.0–18	`off`	—	off
PG19 Beta 3	`on`	—	on

How it works

log_lock_waits logs long lock waits. A wait is logged after deadlock_timeout, so the diagnostic threshold and deadlock detector cadence are coupled.

log_lock_waits 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_lock_waits 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_lock_waits telemetry, but account for long statements, large bind values, and bursty completion patterns in the log pipeline.
Small nodes	Keep log_lock_waits 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`	same as boot	`'on'`
OLAP	`on`	same as boot	`'on'`
CRIT	`on`	same as boot	`'on'`
TINY	`on`	same as boot	`'on'`

Caution

Advice — pending human review. Fact from the current Pigsty template projection: OLTP: PG9.0–19 Beta 3 = on (dcs); OLAP: PG9.0–19 Beta 3 = on (dcs); CRIT: PG9.0–19 Beta 3 = on (dcs); TINY: PG9.0–19 Beta 3 = on (dcs). Advice, pending human review — Editorial inference: All profiles retain long-lock-wait evidence because it is high-value for diagnosing latency and blockers at modest normal volume.

Common pitfalls

Changing log_lock_waits 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 deadlock_timeout without realizing it also changes when lock-wait diagnostics appear.

log_checkpoints · log_autovacuum_min_duration · log_lock_failures · log_temp_files · log_replication_commands