Merge pull request rails#53687 from andyatkinson/docs/rails-guides-postgresql-timestamp-with-time-zone

Rails Guides: PostgreSQL timestamp with time zone [ci skip]

Author: Edouard-chin

guides/source/active_record_postgresql.md

@@ -516,6 +516,34 @@ irb> event.duration
 => 2 days
 ```
 
+### Timestamps
+
+* [Date/Time Types](https://www.postgresql.org/docs/current/datatype-datetime.html)
+
+Rails migrations with timestamps store the time a model was created or updated. By default and for legacy reasons, the columns use the `timestamp without time zone` data type.
+
+```ruby
+# db/migrate/20241220144913_create_devices.rb
+create_table :post, id: :uuid do |t|
+  t.datetime :published_at
+  # By default, Active Record will set the data type of this column to `timestamp without time zone`.
+end
+```
+
+While this works ok, [PostgreSQL best practices](https://wiki.postgresql.org/wiki/Don't_Do_This#Don.27t_use_timestamp_.28without_time_zone.29) recommend that `timestamp with time zone` is used instead for timezone-aware timestamps.
+This must be configured before it can be used for new migrations.
+
+To configure `timestamp with time zone` as your new timestamp default data type, place the following configuration in the `config/application.rb` file.
+
+```ruby
+# config/application.rb
+ActiveSupport.on_load(:active_record_postgresqladapter) do
+  self.datetime_type = :timestamptz
+end
+```
+
+With that configuration in place, generate and apply new migrations, then verify their timestamps use the `timestamp with time zone` data type.
+
 UUID Primary Keys
 -----------------