autovacuum_max_parallel_workers

autovacuum_max_parallel_workers — Maximum number of parallel workers that can be used by a single autovacuum worker. Observed in PG19 Beta 3; its last measured boot default is 0 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: “Maximum number of parallel workers that can be used by a single autovacuum worker.”

Identity

Type , Valueinteger: Upstream pg_settings type
Context , Valuesighup: Takes effect after configuration reload
Unit , Value—: Raw unit
Range , Value0 – 1024: Raw limits in the last observed version
Enum values , Value—: — for non-enum types
Category , ValueVacuuming / Automatic Vacuuming: Upstream classification
Latest boot value , Value0: 0

Lifecycle

Fact	Value
First observed	PG19 Beta 3
Present in	PG19 Beta 3
Removed in	No
Introduction commit	`1ff3180ca016` — Allow autovacuum to use parallel vacuum workers.
Commit date	2026-04-06
Discussion	thread 1

Default history

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

How it works

PostgreSQL describes autovacuum_max_parallel_workers as follows: “Maximum number of parallel workers that can be used by a single autovacuum worker.” A configuration reload applies the value to the server without a full restart. The atlas measures it in PG19 Beta 3; boot_val is the compiled or initialized baseline, not proof of a running cluster’s effective setting.

The limit applies per autovacuum worker and only to index vacuuming and index-cleanup phases. Zero disables parallel autovacuum; the actual count is also capped by max_parallel_workers, while each participating worker consumes CPU and maintenance memory.

Read it together with autovacuum_max_workers, autovacuum_worker_slots, max_parallel_workers, maintenance_work_mem. Check SHOW and pg_settings on the target server, verify the source and pending_restart fields, and compare workload, logs, and resource metrics before and after any change.

Tuning advice

Tip

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

Workload	Guidance
OLTP	Start at the upstream default and use pg_stat_autovacuum_scores, table churn, freeze age, queueing, and foreground latency to justify a change. Protect wraparound work and avoid letting a busy-table preference starve quieter tables.
OLAP	Batch-heavy systems can benefit from prioritizing the largest maintenance debt or parallelizing index cleanup, but benchmark I/O saturation, maintenance memory, worker contention, and completion time across the whole maintenance window.
Small nodes	Keep weights and parallelism conservative. One extra worker can be a large share of CPU, RAM, and storage queue depth; first fix thresholds and ensure autovacuum has enough time to finish.

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: PG19 Beta 3 unmodified; OLAP: PG19 Beta 3 unmodified; CRIT: PG19 Beta 3 unmodified; TINY: PG19 Beta 3 unmodified. No Pigsty-specific rationale is inferred from an absent override.

Common pitfalls

Treating the measured boot_val for autovacuum_max_parallel_workers as proof of the effective value on an initialized or managed cluster.
Applying a change as though it were immediate while pg_settings reports sighup context.
Changing this setting in isolation without checking the linked limits, observability, and rollback path.
Depending on beta behavior in production without retesting the PostgreSQL 19 final release.

autovacuum_max_workers · autovacuum_worker_slots · max_parallel_workers · maintenance_work_mem · autovacuum_work_mem