log_min_duration_statement

Logs every completed statement whose duration reaches a threshold. It is a deterministic slow-query capture control, distinct from sampling and from statement cancellation.

Note

Fact — official short description: “Sets the minimum execution time above which all statements will be logged.”

Identity

Type , Valueinteger: Upstream pg_settings type
Context , Valuesuperuser: Settable at runtime by a superuser
Unit , Valuems: Raw unit
Range , Value-1 – 2147483647: Raw limits in the last observed version
Enum values , Value—: — for non-enum types
Category , ValueReporting and Logging / When to Log: Upstream classification
Latest boot value , Value-1: -1 ms

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
PG9.0–19 Beta 3	`-1`	`ms`	-1 ms

How it works

The value is a duration in milliseconds when no unit is written. A value of -1 disables duration-based statement logging, zero logs every completed statement, and a positive value logs statements at or above the threshold.

Statements selected by this setting are always logged rather than sampled, so it takes priority over log_min_duration_sample. Under the extended query protocol, Parse, Bind, and Execute durations can appear separately.

This parameter observes and records completed work; it does not stop slow statements. statement_timeout is the separate execution-cancellation control.

Tuning advice

Tip

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

Workload	Guidance
OLTP	Choose a threshold from the application’s latency objective and expected log volume. At high QPS, combine a meaningful hard threshold with sampled logging for the faster population.
OLAP	Use a higher threshold so normal long analytical work does not flood logs. Pair logs with query identifiers and workload labels so repeated reports remain actionable.
Small nodes	A low threshold can be useful while tuning, but watch disk use and rotation. Raise it or switch to sampling when logging becomes a measurable part of the workload.

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	`100`	different	`100`
OLAP	`1000`	different	`1000`
CRIT	`100`	different	`100`
TINY	`100`	different	`100`

Caution

Advice — pending human review. Fact from the current Pigsty template projection: OLTP: PG9.0–19 Beta 3 = 100 (dcs); OLAP: PG9.0–19 Beta 3 = 1000 (dcs); CRIT: PG9.0–19 Beta 3 = 100 (dcs); TINY: PG9.0–19 Beta 3 = 100 (dcs). Advice, pending human review — Editorial hypothesis, pending maintainer review: Pigsty opts into deterministic slow-query evidence, while OLAP uses a looser threshold to accommodate naturally longer analytical statements.

Common pitfalls

Low thresholds on high-throughput systems can create extreme log volume and I/O.
SQL text can contain sensitive literals and must be protected like application data.
It logs slow statements but does not cancel them; use statement_timeout for that goal.
Extended-protocol phases may be logged separately and need session or PID correlation.
Interactions with log_statement, sampling, and log_line_prefix can confuse duplicate or fragmented entries.

log_min_duration_sample · log_statement_sample_rate · log_statement · log_duration · log_line_prefix · statement_timeout