Testing Compatibility with oracle using original reference
postgres_vs_oracle2.htm

Available with enterprise db

SEQUENCE:  A sequence is a database object

Oracle's sequence : sequence_name.nextval, SCOTT is a schema that includes the EMP, DEPT and BONUS tables with various grants or privileges.
Postgres's sequence : nextval('sequence_name').

Oracle : schema and users by default are the same. A schema is a collection of database objects like table, views, sequences , stored procedure, added under an user.
PostgreSQL : schema is a namespace, containing objects like table, operators, functions and others, as shown below. This namespace is supposed to be granted to the users.

Please refer : http://www.postgresql.org/docs/9.3/static/sql-createschema.html "CREATE SCHEMA IF NOT EXISTS test AUTHORIZATION joe;"

What is Sequence:


EXEC DBMS_OUTPUT.SERVEROUTPUT(FALSE);

DECLARE
v_emprec VARCHAR2(120);
CURSOR emp_cur IS SELECT * FROM emp ORDER BY empno;
BEGIN
DBMS_OUTPUT.ENABLE;
FOR i IN emp_cur LOOP
v_emprec := i.empno || ',' || i.ename || ',' || i.job || ',' ||
NVL(LTRIM(TO_CHAR(i.mgr,'9999')),'') || ',' || i.hiredate ||
',' || i.sal || ',' ||
NVL(LTRIM(TO_CHAR(i.comm,'9990.99')),'') || ',' || i.deptno;
DBMS_OUTPUT.PUT_LINE(v_emprec);
END LOOP;
END;

CREATE TABLE messages1 (
status INTEGER,
msg VARCHAR2(100)
);

DECLARE
v_line VARCHAR2(100);
v_status INTEGER := 0;
BEGIN
DBMS_OUTPUT.GET_LINE(v_line,v_status);
WHILE v_status = 0 LOOP
INSERT INTO messages1 VALUES(v_status, v_line);
DBMS_OUTPUT.GET_LINE(v_line,v_status);
END LOOP;
END;

SELECT msg FROM messages1;
 

Note the table created under default schema 0; ( to repeat this example / drop the table and run again)." DROP TABLE IF EXISTS messages1;"