REDO

SYS@newtest>select group#,members,status from v$log;

GROUP#    MEMBERS STATUS

---

     1          1 INACTIVE
     2          1 INACTIVE
     3          1 CURRENT

SQL> select * from v$log;

GROUP#    THREAD#  SEQUENCE#      BYTES  BLOCKSIZE    MEMBERS ARCHIVED STATUS           FIRST_CHANGE# FIRST_TIME  NEXT_CHANGE# NEXT_TIME       CON_ID

---

     1          1         73  209715200        512          1 YES      INACTIVE               4361569 2018/1/10 9      4414925 2018/1/10 2          0
     2          1         74  209715200        512          1 YES      INACTIVE               4414925 2018/1/10 2      4438662 2018/1/11 2          0
     3          1         75  209715200        512          1 NO       CURRENT                4438662 2018/1/11 2 1.8446744073                      0

SQL> alter system switch logfile;

alter system switch logfile

ORA-65040: operation not allowed from within a pluggable database
切换后
SQL> select * from v$log;

GROUP#    THREAD#  SEQUENCE#      BYTES  BLOCKSIZE    MEMBERS ARCHIVED STATUS           FIRST_CHANGE# FIRST_TIME  NEXT_CHANGE# NEXT_TIME       CON_ID

---

     1          1         73  209715200        512          1 YES      INACTIVE               4361569 2018/1/10 9      4414925 2018/1/10 2          0
     2          1         74  209715200        512          1 YES      INACTIVE               4414925 2018/1/10 2      4438662 2018/1/11 2          0
     3          1         75  209715200        512          1 NO       CURRENT                4438662 2018/1/11 2 1.8446744073                      0

SQL> alter system switch logfile;

System altered
SQL> select * from v$log;

GROUP#    THREAD#  SEQUENCE#      BYTES  BLOCKSIZE    MEMBERS ARCHIVED STATUS           FIRST_CHANGE# FIRST_TIME  NEXT_CHANGE# NEXT_TIME       CON_ID

---

     1          1         76  209715200        512          1 NO       CURRENT                4457139 2018/1/11 1 1.8446744073                      0
     2          1         74  209715200        512          1 YES      INACTIVE               4414925 2018/1/10 2      4438662 2018/1/11 2          0
     3          1         75  209715200        512          1 YES      ACTIVE                 4438662 2018/1/11 2      4457139 2018/1/11 1          0

SQL> select * from emp where empno=7839;

EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO

---

7839 KING PRESIDENT 1981/11/17 5000.00 10

SQL> update emp set sal=9000 where empno=7839;

1 row updated

SQL> commit;

Commit complete

SQL> select sid,serial#,username from v$session where username='SYS';

   SID    SERIAL# USERNAME

---

    22       1392 SYS
    26      41221 SYS
    55      19525 SYS
    71      13870 SYS
    73      45653 SYS

SQL> SELECT SID FROM V$MYSTAT WHERE ROWNUM =1;

   SID

---

    55
            另一个session
            SQL> alter system dump logfile 'C:\app\Administrator\virtual\oradata\newtest\redo01.log';

System altered

SQL> select value from v$diag_info where name='Default Trace File';

VALUE

C:\APP\ADMINISTRATOR\VIRTUAL\diag\rdbms\newtest\newtest\trace\newtest_ora_32512.trc












在10g中ORACLE会自动调整它的值，他遵循这样一个原则，
'Fixed SGA Size'+ 'Redo Buffers'是granule size的整数倍
这是从oracle9开始出现的新特性