How to set the resolution of the TSTZRANGE Postgres type?

Postgres supports range types_(permalink) such as int4range or tstzrange. The documentation for tstzrange is "Range of timestamp with time zone".

The default precision for timestamps is to use 6 digits for second fractions (microsecond resolution), however my application uses 3 digits for its timestamps (millisecond) through timestamp (3) with time zone. For consistency I would like to also use millisecond-resolution for my time periods.

What is the default tstzrange resolution? How can I configure it?

I tried to define my table using tstzrange(3) but this form is not supported. Applied to the example from the documentation, it would look like:

CREATE TABLE reservation (
    during tstzrange(3),
    EXCLUDE USING GIST (during WITH &&)
);

As of Postgres 13, the time resolution for tstzrange uses 6 digit for second fractions (microsecond resolution). This resolution cannot be changed.

To create a range between timestamps with a custom resolution, you have to define a new range type. Here is the query to create a timestamp range with a millisecond resolution:

CREATE TYPE tstzrange3 AS RANGE (
  subtype = timestamp (3) with time zone
);

This defines both the tstzrange3 type as well as a constructor function with the same name.

You can use this type like any other range:

CREATE TABLE reservation (
    during tstzrange3,
    EXCLUDE USING GIST (during WITH &&)
);

INSERT INTO reservation(during) VALUES(tstzrange3(NOW(), NULL));