timezone_abbreviations

Definition PG 18 manual

Sets the collection of additional time zone abbreviations that will be accepted by the server for datetime input (beyond any abbreviations defined by the current TimeZone setting). The default is 'Default', which is a collection that works in most of the world; there are also 'Australia' and 'India', and other collections can be defined for a particular installation. See Section B.4 for more information.

How it works

timezone_abbreviations selects a file of time zone abbreviations. The selected set changes accepted datetime input tokens and can make the same abbreviation resolve differently by region.

timezone_abbreviations is a USER-context setting. An authorized role can change it for a session, while ALTER ROLE or ALTER DATABASE can establish a default for future sessions.

It changes representation, parsing, or locale behavior at the client boundary rather than physical storage. Coordinate it with the other locale and formatting settings and with driver-native binary or typed protocols.

Operational considerations

Changing timezone_abbreviations in one session and assuming role defaults, database defaults, or other pooled sessions changed with it.

Assuming a presentation setting changes stored values or server-side type semantics.

Changing a role or database default without testing text-parsing clients, exports, and pooled sessions.

Accepting a region-specific abbreviation set that gives familiar tokens a different UTC offset.

Workload guidance

OLAP: Pin timezone_abbreviations for export, reporting, and reproducible analytical jobs; prefer explicit SQL formatting when a file or API has a durable schema.

OLTP: Treat timezone_abbreviations as an application contract, not a performance knob. Standardize it per role or connection pool and keep wire formats explicit where clients parse text.

SMALL: Keep the upstream or locale-derived value unless a client requires another one. A smaller server gains no capacity from changing timezone_abbreviations.