on commit delete rows and on commit preserve rows

ON COMMIT
The ON COMMIT clause is relevant only if you are creating a temporary table. This clause specifies whether the data in the temporary table persists for the duration of a transaction or a session.

DELETE ROWS
Specify DELETE ROWS for a transaction-specific temporary table (this is the default). Oracle will truncate the table (delete all its rows) after each commit.

PRESERVE ROWS
Specify PRESERVE ROWS for a session-specific temporary table. Oracle will truncate the table (delete all its rows) when you terminate the session.