application_name

application_name is the PostgreSQL setting that defines the application name to be reported in statistics and logs.

Note

Fact — official short description: “Sets the application name to be reported in statistics and logs.”

Identity

Type , Valuestring: Upstream pg_settings type
Context , Valueuser: Settable by an ordinary user
Unit , Value—: Raw unit
Range , Value—: Raw limits in the last observed version
Enum values , Value—: — for non-enum types
Category , ValueReporting and Logging / What to Log: Upstream classification
Latest boot value , Value"": empty string

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	`""`	—	empty string

How it works

application_name is client-supplied session metadata, usually set in the startup packet or later with SET. It appears in pg_stat_activity and CSV logs and can be inserted into text logs with the %a escape in log_line_prefix.

The value is shorter than NAMEDATALEN bytes (64 characters in a standard build). PostgreSQL permits printable ASCII; other characters are rendered as C-style hexadecimal escapes. Truncation and escaping mean log consumers must not assume the displayed value exactly matches an application’s original string.

It is a USER-context label and is not authenticated identity: any authorized client can claim a misleading value and a pooled session can retain or overwrite it. Correlate it with authenticated user, database, session ID, remote endpoint, and controlled pool checkout/reset behavior.

Tuning advice

Tip

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

Workload	Guidance
OLTP	Require each service and pooler to set a short, stable, non-secret application_name at checkout and reset it before reuse. Use controlled naming conventions, but never authorize or audit solely from this value.
OLAP	Set a stable job or tool family label and place run-specific high-cardinality identity elsewhere. Correlate long analytical sessions with authenticated role and session ID.
Small nodes	Keep labels compact and useful; node size is irrelevant. Avoid embedding tenant IDs, tokens, SQL, or unbounded request identifiers in a 64-character client-controlled field.

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

Treating application_name as authenticated identity or using it alone for authorization, billing, or audit attribution.
Exceeding NAMEDATALEN and silently losing distinguishing suffixes through truncation.
Assuming arbitrary Unicode is preserved rather than escaped to printable C-style hexadecimal sequences.
Leaking secrets or creating unbounded cardinality in logs and pg_stat_activity, or failing to reset the value in a connection pool.

cluster_name · update_process_title · log_line_prefix · log_timezone · log_hostname