post_auth_delay

post_auth_delay — Sets the amount of time to wait after authentication on connection startup. Observed in PG9.0–19 Beta 3; its last measured boot default is 0 s in PG19 Beta 3, with backend context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA.

Note

Fact — official short description: “Sets the amount of time to wait after authentication on connection startup.”

Identity

Type , Valueinteger: Upstream pg_settings type
Context , Valuebackend: Fixed when a backend starts
Unit , Values: Raw unit
Range , Value0 – 2147: Raw limits in the last observed version
Enum values , Value—: — for non-enum types
Category , ValueDeveloper Options: Upstream classification
Latest boot value , Value0: 0 s

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`	`s`	0 s

How it works

post_auth_delay pauses a newly created backend after authentication succeeds, giving a developer time to attach a debugger to that process. Zero disables the delay.

The backend-context value is fixed at session start. Authentication has completed, so the session and server resources are already allocated while it sleeps.

This intentionally increases connection latency and can consume backend slots under connection storms. It is not a throttling, security, or connection-pooling control. Its backend context fixes the value during connection startup; an existing session cannot change it.

Tuning advice

Tip

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

Workload	Guidance
OLTP	Do not tune production OLTP with post_auth_delay. Enable it only for a bounded reproduction with an owner, log/disk budget, rollback condition, and evidence-capture plan; restore the default immediately afterward.
OLAP	Long analytical runs can amplify post_auth_delay’s debug overhead and artifacts. Prefer standard EXPLAIN and statistics first, and isolate any developer experiment from normal users.
Small nodes	Keep post_auth_delay at its upstream default. A small host has less spare CPU, disk, connection, and log capacity for developer instrumentation.

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: PG9.0–19 Beta 3 unmodified; OLAP: PG9.0–19 Beta 3 unmodified; CRIT: PG9.0–19 Beta 3 unmodified; TINY: PG9.0–19 Beta 3 unmodified. No Pigsty-specific rationale is inferred from an absent override.

Common pitfalls

Leaving post_auth_delay enabled after the bounded diagnostic or recovery task.
Running the experiment on the only copy of production data.
Underestimating log, core-file, temporary-file, WAL, CPU, or connection-slot amplification.
Treating a server that merely starts or completes a query as proof that data and behavior are correct.

pre_auth_delay · authentication_timeout · max_connections · log_connections