CREATE TABLE TESTTAB ( 
    ID NUMBER GENERATED ALWAYS AS IDENTITY, 
    VAL VARCHAR2(20) 
)

INSERT ALL 
   INTO TESTTAB (VAL) VALUES ('VAL1') 
   INTO TESTTAB (VAL) VALUES ('VAL2') 
   INTO TESTTAB (VAL) VALUES ('VAL3') 
SELECT 1 FROM DUAL

CREATE FUNCTION AS_OF (p_tab in DBMS_TF.TABLE_T, p_time in DATE) RETURN VARCHAR2 SQL_MACRO IS 
BEGIN 
RETURN 'SELECT * FROM p_tab AS OF TIMESTAMP(p_time)'; 
END AS_OF; 

declare    
  n number;    
begin    
  for i in 1 .. 500000 loop    
    n := ln(power(sqrt(i), 3));    
  end loop;    
end;   

DELETE FROM TESTTAB WHERE VAL = 'VAL2'

SELECT * FROM TESTTAB

SELECT * FROM TESTTAB AS OF TIMESTAMP(SYSTIMESTAMP - INTERVAL '2' SECOND)

SELECT * FROM AS_OF(TESTTAB,SYSTIMESTAMP - INTERVAL '2' SECOND)