切換歸檔模式後後臺程式的情況

wzz123snow發表於2012-12-04
原文網址 : http://blog.itpub.net/26084062/viewspace-750496/
模式
做了個小實驗，看看將資料庫改為歸檔模式的情況下，後臺程式的啟動情況。
 
SQL> select distinct name,description from v$bgprocess where paddr<>'00'
NAME  DESCRIPTION
----- ----------------------------------------------------------------
CKPT  checkpoint
QMNC  AQ Coordinator
MMNL  Manageability Monitor Process 2
PSP0  process spawner 0
DBW0  db writer process 0
SMON  System Monitor Process
RECO  distributed recovery
PMON  process cleanup
CJQ0  Job Queue Coordinator
LGWR  Redo etc.
MMON  Manageability Monitor Process
NAME  DESCRIPTION
----- ----------------------------------------------------------------
MMAN  Memory Manager
12 rows selected.
--非歸檔模式下啟動了12個程式
SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup mount
ORACLE instance started.
Total System Global Area  167772160 bytes
Fixed Size                  1247876 bytes
Variable Size              71304572 bytes
Database Buffers           88080384 bytes
Redo Buffers                7139328 bytes
Database mounted.
SQL> alter database archivelog;
Database altered.
SQL> alter database open;
Database altered.
SQL> select distinct name,description from v$bgprocess where paddr<>'0
NAME  DESCRIPTION
----- ----------------------------------------------------------------
ARC2  Archival Process 2
CKPT  checkpoint
QMNC  AQ Coordinator
MMNL  Manageability Monitor Process 2
PSP0  process spawner 0
DBW0  db writer process 0
SMON  System Monitor Process
RECO  distributed recovery
PMON  process cleanup
CJQ0  Job Queue Coordinator
LGWR  Redo etc.
NAME  DESCRIPTION
----- ----------------------------------------------------------------
MMON  Manageability Monitor Process
MMAN  Memory Manager
ARC0  Archival Process 0
ARC1  Archival Process 1
15 rows selected.
--改為歸檔模式後，後臺啟動了15個程式，多出的三個程式是ARC0 ，ARC1，ARC2
SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup mount
ORACLE instance started.
Total System Global Area  167772160 bytes
Fixed Size                  1247876 bytes
Variable Size              71304572 bytes
Database Buffers           88080384 bytes
Redo Buffers                7139328 bytes
Database mounted.
SQL> alter database noarchivelog
  2  ;
Database altered.
SQL> alter database open;
Database altered.
SQL> select distinct name,description from v$bgprocess where paddr<>'00';
NAME  DESCRIPTION
----- ----------------------------------------------------------------
CKPT  checkpoint
QMNC  AQ Coordinator
MMNL  Manageability Monitor Process 2
PSP0  process spawner 0
DBW0  db writer process 0
SMON  System Monitor Process
RECO  distributed recovery
PMON  process cleanup
CJQ0  Job Queue Coordinator
LGWR  Redo etc.
MMON  Manageability Monitor Process
NAME  DESCRIPTION
----- ----------------------------------------------------------------
MMAN  Memory Manager
12 rows selected.
--再切換回非歸檔模式，後臺程式又變為12個。

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