Do I need special privileges to create temporary tables in a database in PostgreSQL?

To verify if your user has the privilege to create temporary segments in a postgreSQL database, use this check:

psql -h localhost -d mydb -U myuser

 SELECT has_database_privilege(current_user, current_database(), 'TEMP');

If the value returned shows:

has_database_privilege
------------------------
 f

To be able to create a temporary table in this database, my user needs privileges to do so:

psql
postgres=# grant temp on database mydb to myser;
GRANT

The same test will now yield true instead of false:

SELECT has_database_privilege(current_user, current_database(), 'TEMP');
 has_database_privilege
------------------------
 t
(1 row)

I can now create a temporary table:

CREATE TEMP TABLE table_counts (table_name text, row_count bigint);

Before the grant, the access privileges for my database was

mydb=> \l+ mydb

  |      Access privileges       |
  +------------------------------+
  | postgres=CTc/postgres       +|
  | myuser=c/postgres           +|
 

After the grant:

  |      Access privileges       |
  +------------------------------+
  | postgres=CTc/postgres       +|
  | myuser=Tc/postgres          +|

Notice how the privileges for "myuser" has a "T" ammended to it. This indicate the permission to create temporary objects.