autovacuum_vacuum_cost_delay

autovacuum_vacuum_cost_delay — Vacuum cost delay in milliseconds, for autovacuum. Observed in PG9.0–19 Beta 3; its last measured boot default is 2 ms 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: “Vacuum cost delay in milliseconds, for autovacuum.”

Identity

Type , Valuereal: Upstream pg_settings type
Context , Valuesighup: Takes effect after configuration reload
Unit , Valuems: Raw unit
Range , Value-1 – 100: Raw limits in the last observed version
Enum values , Value—: — for non-enum types
Category , ValueVacuuming / Automatic Vacuuming: Upstream classification
Latest boot value , Value2: 2 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
PG9.0–11	`20`	`ms`	20 ms
PG12–19 Beta 3	`2`	`ms`	2 ms

How it works

Vacuum cost delay in milliseconds, for autovacuum. A configuration reload applies a new value; existing work already in flight is not retroactively changed.

These values govern cost throttling for autovacuum workers; -1 inherits vacuum_cost_delay or vacuum_cost_limit respectively. With multiple active workers, the autovacuum cost budget is balanced among them, so a per-worker reading is not simply multiplied by concurrency.

Monitor and change autovacuum_vacuum_cost_delay together with vacuum_cost_delay, vacuum_cost_limit, vacuum_cost_page_hit. 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	Tune autovacuum_vacuum_cost_delay from autovacuum duration, dead-tuple growth, and foreground I/O latency together. Prefer per-table overrides for hotspots; global throttling must not let cleanup fall permanently behind.
OLAP	During post-load windows, a larger budget or shorter delay can improve maintenance throughput, but verify that scans do not starve queries/imports. Failsafe activation means normal pacing already failed.
Small nodes	Keep conservative defaults. On slow disks, lowering concurrency or overriding one table is usually more controllable than making the delay arbitrarily large.

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	`-1`	different	`-1`
OLAP	`-1`	different	`-1`
CRIT	`-1`	different	`-1`
TINY	`-1`	different	`-1`

Caution

Advice — pending human review. Fact from the current Pigsty template projection: OLTP: PG9.0–19 Beta 3 = -1 (dcs); OLAP: PG9.0–19 Beta 3 = -1 (dcs); CRIT: PG9.0–19 Beta 3 = -1 (dcs); TINY: PG9.0–19 Beta 3 = -1 (dcs). Advice, pending human review — Editorial interpretation, pending human maintainer review: the override appears intended to delegate autovacuum delay to the ordinary vacuum cost setting via the -1 inheritance value; confirm it against the current Pigsty templates, hardware fixture, and operational guarantees before publication.

Common pitfalls

Changing the global value while a table storage parameter overrides it.
Treating reltuples and cumulative change statistics as exact real-time counts.
Blaming a threshold without checking long transactions, replication slots, and worker saturation.
Buying short-term quiet by deferring maintenance until wraparound failsafe activates.

vacuum_cost_delay · vacuum_cost_limit · vacuum_cost_page_hit · vacuum_cost_page_miss · vacuum_cost_page_dirty · autovacuum_vacuum_cost_limit