Selects the method for making timing measurements using the OS or specialized CPU instructions.
At a glance
| Property | Value |
|---|---|
| Parameter | timing_clock_source |
| Category | Resource Consumption |
| Default | (see documentation) |
| Value type | enum |
| Change scope | Per-session (SET) |
| Available in | PostgreSQL 19 (added in 19) |
What it does
Selects the method for making timing measurements using the OS or specialized CPU instructions. Possible values are: auto (automatically chooses TSC clock source on supported x86-64 CPUs, otherwise uses the OS system clock)
system (measures timing using the OS system clock)
(Description quoted from the official PostgreSQL documentation.)
How to apply a change
Can be set per session with SET, per role/database with ALTER ROLE/DATABASE ... SET, or globally in postgresql.conf.
Inspect the current value and source with SHOW timing_clock_source; or SELECT name, setting, unit, context, source FROM pg_settings WHERE name = 'timing_clock_source';.
Tuning guidance
This parameter is rarely a performance lever. Leave it at the default unless you have a specific, documented reason to change it, change it on one session or one role/database first, and confirm the effect with pg_settings and your own measurements before rolling it out cluster-wide.