In PostgreSQL 9.2.3 I am trying to create this simplified table:

CREATE TABLE test (
    user_id INTEGER,
    startend TSTZRANGE,
    EXCLUDE USING gist (user_id WITH =, startend WITH &&)
);


But I get this error:


ERROR:  data type integer has no default operator class for access method "gist"
HINT:  You must specify an operator class for the index or define
       a default operator class for the data type.



The PostgreSQL docs use this example which does not work for me:

CREATE TABLE room_reservation (
    room text,
    during tsrange,
    EXCLUDE USING gist (room WITH =, during WITH &&)
);


Same error message.

And this one, which does not work for me either:

CREATE TABLE zoo (
    cage   INTEGER,
    animal TEXT,
    EXCLUDE USING gist (cage WITH =, animal WITH <>)
);


Same error message.

I am able to create this without any problem:

CREATE TABLE test (
    user_id INTEGER,
    startend TSTZRANGE,
    EXCLUDE USING gist (startend WITH &&)
);


and this:

CREATE TABLE test (
    user_id INTEGER,
    startend TSTZRANGE,
    EXCLUDE USING btree (user_id WITH =)
);


I've spent quite a bit of time searching for hints about figuring out how to make this work, or figuring out why it won't work. Any ideas?

Install the additional module btree_gist as is mentioned in the manual at the location you linked to:

You can use the btree_gist extension to define exclusion constraints
on plain scalar data types, which can then be combined with range
exclusions for maximum flexibility. For example, after btree_gist is
installed, the following constraint will reject overlapping ranges
only if the meeting room numbers are equal:

In modern PostgreSQL you only need to run (once per database):
CREATE EXTENSION btree_gist;

You need to have the "contrib" package installed in your OS first. Details depend on your OS and the software repository used. For the Debian family it's typically postgresql-contrib-13 (for Postgres 13). Or just postgresql-contrib for the Red Hat family. Consider this related answer on SO:

Error when creating unaccent extension on PostgreSQL

