recursive_worktable_factor

recursive_worktable_factor — Sets the planner’s estimate of the average size of a recursive query’s working table. Observed in PG15–19 Beta 3; its last measured boot default is 10 in PG19 Beta 3, with user context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA.

Note

Fact — official short description: “Sets the planner’s estimate of the average size of a recursive query’s working table.”

Identity

Type , Valuereal: Upstream pg_settings type
Context , Valueuser: Settable by an ordinary user
Unit , Value—: Raw unit
Range , Value0.001 – 1e+06: Raw limits in the last observed version
Enum values , Value—: — for non-enum types
Category , ValueQuery Tuning / Other Planner Options: Upstream classification
Latest boot value , Value10: 10

Lifecycle

Fact	Value
First observed	PG15
Present in	PG15–19 Beta 3
Removed in	No
Introduction commit	`0bd7af082ace` — Invent recursive_worktable_factor GUC to replace hard-wired constant.
Commit date	2022-03-24
Discussion	thread 1

Default history

Measured PG9.0–19 Beta 3 boot defaults
Versions	Raw `boot_val`	Unit	Human value
PG15–19 Beta 3	`10`	—	10

How it works

recursive_worktable_factor estimates the average recursive working-table size as a multiple of the non-recursive seed term. The estimate feeds costs for joining the worktable to other relations.

It does not cap recursion, memory, rows, or iterations. A low-fan-out traversal can be modeled with a smaller value, while graph expansion with high fan-out may need a larger estimate.

The value is used during planning; actual recursive growth still depends on data and termination predicates. Misestimation can select an unsuitable join method inside the recursive term. Its user context permits session- or transaction-local changes; newly performed or newly planned work sees the value.

Tuning advice

Tip

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

Workload	Guidance
OLTP	Keep recursive_worktable_factor at its upstream default unless representative plans show a repeatable, workload-wide problem. Test a local override first and include planning latency as well as execution latency.
OLAP	Analytical SQL can make recursive_worktable_factor more visible because joins, cursors, or recursion are larger. Benchmark the full statement family and inspect estimates rather than copying a single successful value.
Small nodes	On a small host, avoid increasing planning search or memory pressure through recursive_worktable_factor without a measured benefit. Prefer query-local structure or a scoped role setting over a cluster-wide override.

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: PG15–19 Beta 3 unmodified; OLAP: PG15–19 Beta 3 unmodified; CRIT: PG15–19 Beta 3 unmodified; TINY: PG15–19 Beta 3 unmodified. No Pigsty-specific rationale is inferred from an absent override.

Common pitfalls

Treating recursive_worktable_factor as an executor resource limit rather than a planning assumption or policy.
Testing only one parameter set or one data distribution.
Expecting an already cached plan to be rewritten automatically.
Using a global override to hide stale statistics or fragile SQL structure.

work_mem · enable_nestloop · enable_hashjoin · default_statistics_target