В справке на селект предусмотрено:

CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } ] TABLE table_name (
{ column_name data_type [ DEFAULT default_expr ] [ column_constraint [, ... ] ]
| table_constraint
| LIKE parent_table [ { INCLUDING | EXCLUDING } DEFAULTS ] } [, ... ]
)
[ INHERITS ( parent_table [, ... ] ) ]
[ WITH OIDS | WITHOUT OIDS ]
[ ON COMMIT { PRESERVE ROWS | DELETE ROWS | DROP } ]

где

TEMPORARY or TEMP
If specified, the table is created as a temporary table. Temporary tables are automatically dropped at the end of a session, or optionally at the end of the current transaction (see ON COMMIT below). Existing permanent tables with the same name are not visible to the current session while the temporary table exists, unless they are referenced with schema-qualified names.


ON COMMIT
The behavior of temporary tables at the end of a transaction block can be controlled using ON COMMIT. The three options are:



PRESERVE ROWS
No special action is taken at the ends of transactions. This is the default behavior.

DELETE ROWS
All rows in the temporary table will be deleted at the end of each transaction block. Essentially, an automatic TRUNCATE is done at each commit.

DROP
The temporary table will be dropped at the end of the current transaction block.


но вот ON COMMIT у меня (работаю из под pgAdmin) вызывает ошибку. В результате (без ON COMMIT), если не отсоединяться, и не дропать таблицу - она остается в отдельной схеме pg_temp_i где i -цифирька. И данные в ей тоже.