CTAS stands for Create Table As Select
e.g.
SQL>
CREATE TABLE HR.EMPLOYEES_NEW
AS
SELECT * FROM HR.EMPLOYEES;
-> By default, only "NOT_NULL" constraints copy to new table (HR.EMPLOYEES_NEW) if it has (HR.EMPLOYEES). (PK, FK, index, etc. does not copy)
CTAS is faster because UNDO and REDO data does not generate. (It use NOLOGGING AND PARALEL methods)
