Contents
clock_timestamp()
clock_timestamp() is a system function returning a timestamp representing the point-in-time the function was executed.
clock_timestamp() was added in PostgreSQL 8.2.
Usage
clock_timestamp ( ) → timestamp with time zone
clock_timestamp() returns the time and date current when the function was executed. In contrast to current_timestamp, which returns the time and date current at the start of the current transaction, the value returned by clock_timestamp() will change for each execution of the function.
Change history
- PostgreSQL 8.2
- added (commit e6004f01)
Examples
Basic execution example for clock_timestamp():
postgres=# SELECT clock_timestamp();
clock_timestamp
-------------------------------
2021-06-17 16:08:07.867682+01
(1 row)
The timestamp returned by clock_timestamp() will increase each time the function is executed within a query:
postgres=# SELECT
clock_timestamp(),
statement_timestamp(),
current_timestamp,
clock_timestamp()\gx
-[ RECORD 1 ]-------+------------------------------
clock_timestamp | 2021-06-17 16:12:37.167085+01
statement_timestamp | 2021-06-17 16:12:37.166871+01
current_timestamp | 2021-06-17 16:12:37.166871+01
clock_timestamp | 2021-06-17 16:12:37.167086+01
In the above query, the values reported for statement_timestamp() and current_timestamp represent the point-in-time when statement execution started, and hence report an earlier time than the first invocation of clock_timestamp().
References
- PostgreSQL documentation: Date/Time Functions
- PostgreSQL documentation: Current Date/Time