stats_temp_directory

stats_temp_directory — Writes temporary statistics files to the specified directory. Observed in PG9.0–14; its last measured boot default is pg_stat_tmp in PG14, with sighup context. It was removed in PG15.

Note

Fact — official short description: “Writes temporary statistics files to the specified directory.”

Identity

Type , Valuestring: Upstream pg_settings type
Context , Valuesighup: Takes effect after configuration reload
Unit , Value—: Raw unit
Range , Value—: Raw limits in the last observed version
Enum values , Value—: — for non-enum types
Category , ValueStatistics / Query and Index Statistics Collector: Upstream classification
Latest boot value , Valuepg_stat_tmp: pg_stat_tmp

Lifecycle

Fact	Value
First observed	PG9.0 (research boundary)
Present in	PG9.0–14
Removed in	PG15
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
PG9.0–14	`pg_stat_tmp`	—	pg_stat_tmp

How it works

Through PG14, stats_temp_directory selected where the old statistics collector wrote temporary statistics files. It did not store durable table statistics created by ANALYZE.

A fast local memory-backed directory could reduce collector file I/O, but loss of its temporary contents was expected. Permissions and directory availability still had to permit the server to operate.

PostgreSQL 15 replaced the collector’s file-based architecture with shared-memory cumulative statistics and removed this GUC. PG15+ migrations must delete the setting rather than map it to another directory. Its SIGHUP context allows configuration reload without a server restart.

Tuning advice

Tip

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

Workload	Guidance
OLTP	Do not tune stats_temp_directory on current PostgreSQL: remove it from upgrade targets and use the current replacement behavior described above. Retain it only when reproducing the historical version.
OLAP	Do not carry stats_temp_directory into a modern analytical cluster. Benchmark the supported current mechanisms instead of trying to emulate a removed implementation detail.
Small nodes	Delete stats_temp_directory during version migration; an unknown-parameter startup failure is more likely than a benefit. Historical test instances should keep the old upstream default.

Pigsty

Values use the fixed 8-vCPU, 32-GiB, 100-GiB SSD fixture and render the current Pigsty templates for PG14; 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: PG9.0–14 unmodified; OLAP: PG9.0–14 unmodified; CRIT: PG9.0–14 unmodified; TINY: PG9.0–14 unmodified. No Pigsty-specific rationale is inferred from an absent override.

Common pitfalls

Changing stats_temp_directory without applying its documented unit and configuration context.
Optimizing an isolated benchmark while ignoring concurrent aggregate resource use.
Assuming a configured value guarantees operating-system or storage behavior.
Failing to retest startup, failover, and workload latency after the change.

stats_fetch_consistency · track_counts · track_activities · data_directory