autovacuum_vacuum_scale_factor

Controls the table-size-proportional part of the normal autovacuum VACUUM trigger. Lower values make large tables eligible after a smaller fraction of rows becomes obsolete.

Note

Fact — official short description: “Number of tuple updates or deletes prior to vacuum as a fraction of reltuples.”

Identity

Type , Valuereal: Upstream pg_settings type
Context , Valuesighup: Takes effect after configuration reload
Unit , Value—: Raw unit
Range , Value0 – 100: Raw limits in the last observed version
Enum values , Value—: — for non-enum types
Category , ValueVacuuming / Automatic Vacuuming: Upstream classification
Latest boot value , Value0.2: 0.2

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	`0.2`	—	0.2

How it works

The core trigger is the base threshold plus this factor multiplied by pg_class.reltuples, an approximate row count. In PostgreSQL 18 the result is also capped by autovacuum_vacuum_max_threshold.

This trigger counts tuples made obsolete by UPDATE or DELETE; insert-driven vacuuming has its own threshold and scale factor. Anti-wraparound vacuuming is governed by transaction-age rules and can run independently of this setting.

A table-level autovacuum_vacuum_scale_factor storage parameter overrides the global value, which is often preferable when table sizes and update rates vary widely.

Tuning advice

Tip

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

Workload	Guidance
OLTP	Use lower per-table values on large, update-heavy tables so dead tuples do not accumulate into a large absolute backlog. Validate with table churn and vacuum duration rather than selecting a percentage in isolation.
OLAP	For append-and-batch workloads, coordinate the threshold with load cycles and explicit VACUUM/ANALYZE. A low global factor can create unwanted maintenance during bulk jobs.
Small nodes	The upstream default is often adequate for genuinely small tables. Tune exceptions per table; a low cluster-wide value can create frequent tiny vacuums.

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	`0.08`	different	`0.08`
OLAP	`0.08`	different	`0.08`
CRIT	`0.08`	different	`0.08`
TINY	Unmodified	—	—

Caution

Advice — pending human review. Fact from the current Pigsty template projection: OLTP: PG9.0–19 Beta 3 = 0.08 (dcs); OLAP: PG9.0–19 Beta 3 = 0.08 (dcs); CRIT: PG9.0–19 Beta 3 = 0.08 (dcs); TINY: PG9.0–19 Beta 3 unmodified. Advice, pending human review — Editorial hypothesis, pending maintainer review: the larger profiles favor earlier cleanup to bound absolute dead-tuple accumulation on sizable tables; TINY avoids extra vacuum frequency on constrained systems.

Common pitfalls

A percentage that looks small can still represent millions of dead tuples on a large table.
Lowering the factor globally can create continuous I/O pressure across many tables.
It does not control insert-triggered vacuuming or anti-wraparound vacuuming.
reltuples is an estimate, so the trigger is not an exact dead-row percentage.
Table storage parameters can silently make the global value irrelevant for that table.

autovacuum_vacuum_threshold · autovacuum_vacuum_max_threshold · autovacuum_vacuum_insert_scale_factor · autovacuum_analyze_scale_factor · autovacuum_naptime · autovacuum_freeze_max_age