Using current time in UTC as default value in PostgreSQL

Question

I have a column of the TIMESTAMP WITHOUT TIME ZONE type and would like to have that default to the current time in UTC. Getting the current time in UTC is easy:

Answer 1

These are 2 equivalent solutions:

(in the following code, you should substitute 'UTC' for zone and now() for timestamp)

1. timestamp AT TIME ZONE zone - SQL-standard-conforming
2. timezone(zone, timestamp) - arguably more readable

The function timezone(zone, timestamp) is equivalent to the SQL-conforming construct timestamp AT TIME ZONE zone.

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Explanation:

• zone can be specified either as a text string (e.g., 'UTC') or as an interval (e.g., INTERVAL '-08:00') - here is a list of all available time zones
• timestamp can be any value of type timestamp
• now() returns a value of type timestamp (just what we need) with your database's default time zone attached (e.g. 2018-11-11T12:07:22.3+05:00).
• timezone('UTC', now()) turns our current time (of type timestamp with time zone) into the timezonless equivalent in UTC.
  E.g., SELECT timestamp with time zone '2020-03-16 15:00:00-05' AT TIME ZONE 'UTC' will return 2020-03-16T20:00:00Z.

Docs: timezone()