oracle-managed files (35)

Oracle-managed files eliminate the need for you, the DBA, to directly manage the
operating system files comprising an Oracle database. You specify operations in terms
of database objects rather than filenames. Oracle internally uses standard file system
interfaces to create and delete files as needed for the following database structures:
1 Tablespaces
2 Redo log files
3 Control files
Through initialization parameters, you specify the file system directory to be used for
a particular type of file. Oracle then ensures that a unique file, an Oracle-managed file,
is created and deleted when no longer needed.

initialization parameters : db_create_file_dest
comprise
包含, 由...組成

再轉一篇文章

為了理解OMF是如何工作的，讓我們首先定義一個叫著DB_CTEATE_FILE_DEST的新引數。

alter system set db_create_file_dest='/u01/oradata/PROD';

一旦設定好了DB_CTEATE_FILE_DEST引數，我們就可以建立表空間而無須指定檔名。

createtablespace
omf1
datafile size 100m
locally managed;

檔案建立之後，Oracle就可以分配和命名這些檔案。Oracle OMF使用如下的命名轉換慣例。預設的檔案大小為100M，並按如下格式命名：

where
%u is a unique 8 digit code
%g is the log file group number
%t is the tablespace name

Controlfiles ora_%u.ctl
Redo Log Files ora_%g_%u.log
Datafiles ora_%t_%u.dbf
Temporary Datafilesora_%t_%u.tmp

Oracle9i OMF工具還有一個新的警告日誌訊息（alert log message），它用來告訴我們OMF資料檔案何時發生了改動。下面是關於警告日誌的一個例子。

Fri Mar 23 01:44:46 2001
CREATE TABLESPACE omf1 DATAFILE SIZE 10M AUTOEXTEND OFF
Fri Mar 23 01:44:47 2001
Created Oracle managed file /databases/ed25/OMF1/ora_omf1_xcp6rg84.dbf
Completed: CREATE TABLESPACE omf1 DATAFILE SIZE 10M AUTOEXTE
Fri Mar 23 01:45:45 2001
drop tablespace omf1
Fri Mar 23 01:45:45 2001
Deleted Oracle managed file /databases/ed25/OMF1/ora_omf_xcp6rg84.dbf
Completed: drop tablespace omf1

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