autovacuum_work_mem

The memory ceiling for each autovacuum worker, with -1 meaning that the worker inherits maintenance_work_mem.

Note

Fact — official short description: “Sets the maximum memory to be used by each autovacuum worker process.”

Identity

Type , Valueinteger: Upstream pg_settings type
Context , Valuesighup: Takes effect after configuration reload
Unit , ValuekB: Raw unit
Range , Value-1 – 2147483647: Raw limits in the last observed version
Enum values , Value—: — for non-enum types
Category , ValueResource Usage / Memory: Upstream classification
Latest boot value , Value-1: -1 kB

Lifecycle

Fact	Value
First observed	PG9.4
Present in	PG9.4–19 Beta 3
Removed in	No
Introduction commit	`8693559cacf1` — New autovacuum_work_mem parameter
Commit date	2013-12-12
Discussion	—

Default history

Measured PG9.0–19 Beta 3 boot defaults
Versions	Raw `boot_val`	Unit	Human value
PG9.4–19 Beta 3	`-1`	`kB`	-1 kB

How it works

autovacuum_work_mem applies separately to each autovacuum worker process. The default sentinel -1 means to use maintenance_work_mem rather than negative memory.

The setting affects autovacuum workers only; it does not change manually issued VACUUM. It is a SIGHUP-context parameter, so it is configured at server level rather than as a per-session tuning knob.

Because multiple workers can run concurrently, the aggregate potential allocation is the per-worker value multiplied by active autovacuum workers. Memory is only one part of vacuum behavior; I/O throttling, worker count, thresholds, and table activity also matter.

Tuning advice

Tip

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

Workload	Guidance
OLTP	When maintenance_work_mem is large, set an explicit lower autovacuum ceiling unless the concurrent-worker budget clearly fits. Watch vacuum duration, dead-tuple backlog, and latency before increasing it.
OLAP	Large relations may justify more memory per worker, but schedule and worker concurrency can dominate. Coordinate the value with autovacuum_max_workers and the maintenance window.
Small nodes	Keep -1 only when maintenance_work_mem is itself conservative; otherwise set a smaller explicit value to prevent several workers from exhausting the host.

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	Unmodified	—	—
OLAP	Unmodified	—	—
CRIT	Unmodified	—	—
TINY	Unmodified	—	—

Caution

Advice — pending human review. Fact from the current Pigsty template projection: OLTP: PG9.4–19 Beta 3 unmodified; OLAP: PG9.4–19 Beta 3 unmodified; CRIT: PG9.4–19 Beta 3 unmodified; TINY: PG9.4–19 Beta 3 unmodified. No Pigsty-specific rationale is inferred from an absent override.

Common pitfalls

Reading -1 as a literal negative kilobyte value instead of an inheritance sentinel.
Assuming the setting controls manual VACUUM.
Budgeting one worker while several autovacuum workers can run at once.
Increasing memory to address a vacuum problem actually caused by I/O throttling, thresholds, locks, or insufficient worker capacity.

maintenance_work_mem · autovacuum_max_workers · autovacuum_worker_slots · vacuum_buffer_usage_limit · autovacuum_vacuum_cost_delay