pgtt

-- create the extension
CREATE EXTENSION pgtt;

After creating the extension, it needs to be loaded before use
You can use one of the following three methods to load it:

1. Modify session_preload_libraries in the configuration file
session_preload_libraries = 'pgtt'

2. Enable at database level
ALTER DATABASE mydb SET session_preload_libraries = 'pgtt';

3. Load in session
LOAD 'pgtt';

After successfully loading the extension, you can see that the value of pgtt.enabled is on
ivorysql=# show pgtt.enabled;
 pgtt.enabled
--------------
 on
(1 row)

pgtt_schema is added to search_path
ivorysql=# SHOW search_path;
         search_path
------------------------------
 "$user", public, pgtt_schema
(1 row)

Create temporary table:
Using this statement will produce a warning message, but it can be ignored.

ivorysql=# CREATE GLOBAL TEMPORARY TABLE test_gtt_table (
	id integer,
	lbl text
) ON COMMIT PRESERVE ROWS;
WARNING:  GLOBAL is deprecated in temporary table creation
LINE 1: CREATE GLOBAL TEMPORARY TABLE test_gtt_table (
               ^
CREATE TABLE

If you don't want to produce this warning message, you can use comment symbols:
CREATE /*GLOBAL*/ TEMPORARY TABLE test_gtt_table (
	id integer,
	lbl text
) ON COMMIT PRESERVE ROWS;


Temporary tables can also be created using the LIKE clause:
ivorysql=# CREATE /*GLOBAL*/ TEMPORARY TABLE test_gtt_table AS SELECT * FROM source_table WITH DATA;
CREATE TABLE AS

Create indexes on table columns:
ivorysql=# CREATE INDEX ON test_gtt_table (id);
CREATE INDEX

Drop temporary table:
ivorysql=# drop table test_gtt_table;
DROP TABLE

Add constraints (except foreign keys):
ivorysql=# CREATE /*GLOBAL*/ TEMPORARY TABLE t2 (
	c1 serial PRIMARY KEY,
	c2 VARCHAR (50) UNIQUE NOT NULL,
	c3 boolean DEFAULT false
);
CREATE TABLE

Creating tables with foreign keys is not allowed:
ivorysql=# CREATE /*GLOBAL*/ TEMPORARY TABLE t1 (c1 integer, FOREIGN KEY (c1) REFERENCES source (id));
ERROR:  attempt to create referential integrity constraint on global temporary table

ivorysql=# ALTER TABLE t2 ADD FOREIGN KEY (c1) REFERENCES source (id);
ERROR:  attempt to create referential integrity constraint on global temporary table