Oralce 18c New feature

Private temporary tables are temporary database objects that are automatically dropped at the end of a transaction or a session. A private temporary table is stored in memory and is visible only to the session that created it.

A private temporary table confines the scope of a temporary table to a session or a transaction, thus providing more flexibility in application coding, leading to easier code maintenance and a better ready-to-use functionality.

When an application stores temporary data in transient tables that are populated once, read few times, and then dropped at the end of a transaction or session

When a session is maintained indefinitely and must create different temporary tables for different transactions

When the creation of a temporary table must not start a new transaction or commit an existing transaction

When different sessions of the same user must use the same name for a temporary table

When a temporary table is required for a read-only database

SQL> show parameter prefix

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
common_user_prefix                   string      C##
os_authent_prefix                    string      ops$
private_temp_table_prefix            string      ORA$PTT_
SQL> 

SQL>  create private temporary table ora$ptt_my_ppt( id number, name varchar2(20)) on commit preserve definition;
 create private temporary table ora$ptt_my_ppt( id number, name varchar2(20)) on commit preserve definition
*
ERROR at line 1:
ORA-14451: unsupported feature with temporary table

SQL>