PG_POSTMASTER_START_TIME

Return the timestamp at which the server process started.

Syntax

PG_POSTMASTER_START_TIME()

Description

## Overview Returns the TIMESTAMP WITH TIME ZONE at which the backend process was started. Use this function to compute server uptime, correlate incidents with deploy times, or include in diagnostic snapshots. ## Session context - The value reflects the whole server, not the session. - Fixed for the lifetime of the process. - Takes no arguments. - Never returns NULL. ## Behavior - Returns a TIMESTAMP WITH TIME ZONE. - Deterministic for a given process. - Side effect free. ## Compatibility - PG-compat alias for `pg_postmaster_start_time` function.

Examples

-- Read the server start time
SELECT PG_POSTMASTER_START_TIME();

-- Calculate server uptime
SELECT CURRENT_TIMESTAMP - PG_POSTMASTER_START_TIME() AS uptime;

-- Include in a diagnostics snapshot
SELECT PG_POSTMASTER_START_TIME() AS started, VERSION() AS engine;

-- Detect that a config reload has occurred after startup
SELECT PG_CONF_LOAD_TIME() > PG_POSTMASTER_START_TIME() AS was_reloaded;

Pitfalls

• Restarts reset this value. When reading uptime for alerting, consider the fact that a brief process restart may not trigger downstream monitoring even though the value changed.
• In clustered deployments, each node reports its own start time. A query routed to a newly started replica may return a very recent value.
• The return type is TIMESTAMPTZ. Subtracting CURRENT_TIMESTAMP yields an INTERVAL; format it with TO_CHAR or FORMAT_STRING if you need a human-readable string.
• The timestamp is the OS-reported start time of the backend process, not the time the cluster or deployment was first created.

See Also

• pg_conf_load_time
• pg_backend_pid
• version