unix_socket_group

unix_socket_group is the PostgreSQL setting that defines the owning group of the Unix-domain socket.

Note

Fact — official short description: “Sets the owning group of the Unix-domain socket.”

Identity

Type , Valuestring: Upstream pg_settings type
Context , Valuepostmaster: Requires a server restart
Unit , Value—: Raw unit
Range , Value—: Raw limits in the last observed version
Enum values , Value—: — for non-enum types
Category , ValueConnections and Authentication / Connection Settings: 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

unix_socket_group sets the owning group of filesystem Unix-domain sockets; the owning user remains the PostgreSQL server account. An empty string uses that account’s default group, and unix_socket_permissions determines which group access bits are usable.

It is a POSTMASTER-context setting, so changing it requires restart and affects sockets recreated at startup. Directory ownership and traversal rights, group membership, and pg_hba.conf local records remain separate access layers.

The setting is unsupported and ignored on Windows. It is also ignored for Linux abstract-namespace sockets selected by an @-prefixed unix_socket_directories entry, because those sockets have no filesystem owner or group.

Tuning advice

Tip

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

Workload	Guidance
OLTP	Choose a dedicated operating-system group only for local tools that need socket reachability, audit its membership, and pair it with 0770-style socket and directory permissions. Test pg_hba.conf authentication separately.
OLAP	Analytical tools should join the same reviewed local-access group or use TCP/TLS; do not create a broad group merely for convenience.
Small nodes	Use the server account’s default group unless a managed local client requires another one. On Windows or abstract sockets, configure the actual applicable access boundary instead because this GUC is ignored.

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

Expecting a reload to change socket ownership; the socket is recreated only at server restart.
Relying on this setting on Windows or for an abstract-namespace socket, where it is ignored.
Granting membership in the socket group without separately enforcing pg_hba.conf authentication and database privileges.
Changing the socket group while directory traversal permissions still prevent intended clients from reaching it.

listen_addresses · port · max_connections · reserved_connections · superuser_reserved_connections · unix_socket_directories