v$datafile.enabled相关值说明

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标题：v$datafile.enabled相关值说明

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自认为对v$datafile视图算比较了解,但是今天看到一网友的v$datafile.enabled=DISABLED,我一时没有想出来是为什么,这里通过试验对v$datafile.enabled各种情况进行了试验并简单说明scn的变化情况
模拟环境(READ WRITE)

SQL> alter tablespace users add datafile '/u01/oracle/oradata/XFF/users02.dbf' size 10m;
Tablespace altered.
SQL> select file#,ts#,CHECKPOINT_CHANGE#,enabled,status,name from v$datafile;
     FILE#        TS# CHECKPOINT_CHANGE# ENABLED    STATUS  NAME
---------- ---------- ------------------ ---------- ------- ---------------------------------------
         1          0             456727 READ WRITE SYSTEM  /u01/oracle/oradata/XFF/system01.dbf
         2          1             456727 READ WRITE ONLINE  /u01/oracle/oradata/XFF/undotbs01.dbf
         3          2             456727 READ WRITE ONLINE  /u01/oracle/oradata/XFF/sysaux01.dbf
         4          4             456727 READ WRITE ONLINE  /u01/oracle/oradata/XFF/users01.dbf
         5          4             458322 READ WRITE ONLINE  /u01/oracle/oradata/XFF/users02.dbf
QL> select file#,status, CHECKPOINT_CHANGE# from v$datafile_header;
     FILE# STATUS  CHECKPOINT_CHANGE#
---------- ------- ------------------
         1 ONLINE              456727
         2 ONLINE              456727
         3 ONLINE              456727
         4 ONLINE              456727
         5 ONLINE              458322

加入数据文件scn不一样是因为:加入数据文件的时候,使用是当前scn,而数据库未做checkpoint,所以出现数据文件scn不一致现象

datafile offline(READ WRITE)

SQL> alter database datafile 5 offline;
Database altered.
SQL> alter system checkpoint;
System altered.
SQL> /
System altered.
SQL> select file#,status, CHECKPOINT_CHANGE# from v$datafile_header;
     FILE# STATUS  CHECKPOINT_CHANGE#
---------- ------- ------------------
         1 ONLINE              458392
         2 ONLINE              458392
         3 ONLINE              458392
         4 ONLINE              458392
         5 OFFLINE             458322
SQL> select file#,ts#,CHECKPOINT_CHANGE#,enabled,status,name from v$datafile;
     FILE#        TS# CHECKPOINT_CHANGE# ENABLED    STATUS  NAME
---------- ---------- ------------------ ---------- ------- ----------------------------------------
         1          0             458392 READ WRITE SYSTEM  /u01/oracle/oradata/XFF/system01.dbf
         2          1             458392 READ WRITE ONLINE  /u01/oracle/oradata/XFF/undotbs01.dbf
         3          2             458392 READ WRITE ONLINE  /u01/oracle/oradata/XFF/sysaux01.dbf
         4          4             458392 READ WRITE ONLINE  /u01/oracle/oradata/XFF/users01.dbf
         5          4             458322 READ WRITE RECOVER /u01/oracle/oradata/XFF/users02.dbf

这里可以看出来数据文件offline之后,v$datafile.enabled依然是READ WRITE,但是该数据文件的scn不再变化

tablespace offline(DISABLED)

SQL> recover datafile 5;
Media recovery complete.
SQL> alter database datafile 5 online;
Database altered.
SQL>  select file#,ts#,CHECKPOINT_CHANGE#,enabled,status,name from v$datafile;
     FILE#        TS# CHECKPOINT_CHANGE# ENABLED    STATUS  NAME
---------- ---------- ------------------ ---------- ------- --------------------------------------
         1          0             458392 READ WRITE SYSTEM  /u01/oracle/oradata/XFF/system01.dbf
         2          1             458392 READ WRITE ONLINE  /u01/oracle/oradata/XFF/undotbs01.dbf
         3          2             458392 READ WRITE ONLINE  /u01/oracle/oradata/XFF/sysaux01.dbf
         4          4             458392 READ WRITE ONLINE  /u01/oracle/oradata/XFF/users01.dbf
         5          4             458430 READ WRITE ONLINE  /u01/oracle/oradata/XFF/users02.dbf
SQL> select file#,status, CHECKPOINT_CHANGE# from v$datafile_header;
     FILE# STATUS  CHECKPOINT_CHANGE#
---------- ------- ------------------
         1 ONLINE              458392
         2 ONLINE              458392
         3 ONLINE              458392
         4 ONLINE              458392
         5 ONLINE              458430
SQL> alter system checkpoint;
System altered.
SQL> select file#,ts#,CHECKPOINT_CHANGE#,enabled,status,name from v$datafile;
     FILE#        TS# CHECKPOINT_CHANGE# ENABLED    STATUS  NAME
---------- ---------- ------------------ ---------- ------- ---------------------------------------
         1          0             458443 READ WRITE SYSTEM  /u01/oracle/oradata/XFF/system01.dbf
         2          1             458443 READ WRITE ONLINE  /u01/oracle/oradata/XFF/undotbs01.dbf
         3          2             458443 READ WRITE ONLINE  /u01/oracle/oradata/XFF/sysaux01.dbf
         4          4             458443 READ WRITE ONLINE  /u01/oracle/oradata/XFF/users01.dbf
         5          4             458443 READ WRITE ONLINE  /u01/oracle/oradata/XFF/users02.dbf
SQL> select file#,status, CHECKPOINT_CHANGE# from v$datafile_header;
     FILE# STATUS  CHECKPOINT_CHANGE#
---------- ------- ------------------
         1 ONLINE              458443
         2 ONLINE              458443
         3 ONLINE              458443
         4 ONLINE              458443
         5 ONLINE              458443
SQL> alter tablespace users offline;
Tablespace altered.
SQL> alter system checkpoint;
System altered.
SQL> /
System altered.
SQL> select file#,ts#,CHECKPOINT_CHANGE#,enabled,status,name from v$datafile;
     FILE#        TS# CHECKPOINT_CHANGE# ENABLED    STATUS  NAME
---------- ---------- ------------------ ---------- ------- --------------------------------------
         1          0             458497 READ WRITE SYSTEM  /u01/oracle/oradata/XFF/system01.dbf
         2          1             458497 READ WRITE ONLINE  /u01/oracle/oradata/XFF/undotbs01.dbf
         3          2             458497 READ WRITE ONLINE  /u01/oracle/oradata/XFF/sysaux01.dbf
         4          4             458457 DISABLED   OFFLINE /u01/oracle/oradata/XFF/users01.dbf
         5          4             458457 DISABLED   OFFLINE /u01/oracle/oradata/XFF/users02.dbf
SQL> select file#,status, CHECKPOINT_CHANGE# from v$datafile_header;
     FILE# STATUS  CHECKPOINT_CHANGE#
---------- ------- ------------------
         1 ONLINE              458497
         2 ONLINE              458497
         3 ONLINE              458497
         4 OFFLINE                  0
         5 OFFLINE                  0
SQL> alter system checkpoint;
System altered.
SQL> /
System altered.
SQL> select file#,ts#,CHECKPOINT_CHANGE#,enabled,status,name from v$datafile;
     FILE#        TS# CHECKPOINT_CHANGE# ENABLED    STATUS  NAME
---------- ---------- ------------------ ---------- ------- --------------------------------------------------
         1          0             458512 READ WRITE SYSTEM  /u01/oracle/oradata/XFF/system01.dbf
         2          1             458512 READ WRITE ONLINE  /u01/oracle/oradata/XFF/undotbs01.dbf
         3          2             458512 READ WRITE ONLINE  /u01/oracle/oradata/XFF/sysaux01.dbf
         4          4             458457 DISABLED   OFFLINE /u01/oracle/oradata/XFF/users01.dbf
         5          4             458457 DISABLED   OFFLINE /u01/oracle/oradata/XFF/users02.dbf
SQL> select file#,status, CHECKPOINT_CHANGE# from v$datafile_header;
     FILE# STATUS  CHECKPOINT_CHANGE#
---------- ------- ------------------
         1 ONLINE              458512
         2 ONLINE              458512
         3 ONLINE              458512
         4 OFFLINE                  0
         5 OFFLINE                  0
SQL> alter tablespace users online;
Tablespace altered.
SQL> select file#,status, CHECKPOINT_CHANGE# from v$datafile_header;
     FILE# STATUS  CHECKPOINT_CHANGE#
---------- ------- ------------------
         1 ONLINE              458512
         2 ONLINE              458512
         3 ONLINE              458512
         4 ONLINE              458526
         5 ONLINE              458526
SQL> select file#,ts#,CHECKPOINT_CHANGE#,enabled,status,name from v$datafile;
     FILE#        TS# CHECKPOINT_CHANGE# ENABLED    STATUS  NAME
---------- ---------- ------------------ ---------- ------- --------------------------------------------------
         1          0             458512 READ WRITE SYSTEM  /u01/oracle/oradata/XFF/system01.dbf
         2          1             458512 READ WRITE ONLINE  /u01/oracle/oradata/XFF/undotbs01.dbf
         3          2             458512 READ WRITE ONLINE  /u01/oracle/oradata/XFF/sysaux01.dbf
         4          4             458526 READ WRITE ONLINE  /u01/oracle/oradata/XFF/users01.dbf
         5          4             458526 READ WRITE ONLINE  /u01/oracle/oradata/XFF/users02.dbf
SQL> alter system checkpoint;
System altered.
SQL> select file#,ts#,CHECKPOINT_CHANGE#,enabled,status,name from v$datafile;
     FILE#        TS# CHECKPOINT_CHANGE# ENABLED    STATUS  NAME
---------- ---------- ------------------ ---------- ------- --------------------------------------------------
         1          0             458551 READ WRITE SYSTEM  /u01/oracle/oradata/XFF/system01.dbf
         2          1             458551 READ WRITE ONLINE  /u01/oracle/oradata/XFF/undotbs01.dbf
         3          2             458551 READ WRITE ONLINE  /u01/oracle/oradata/XFF/sysaux01.dbf
         4          4             458551 READ WRITE ONLINE  /u01/oracle/oradata/XFF/users01.dbf
         5          4             458551 READ WRITE ONLINE  /u01/oracle/oradata/XFF/users02.dbf
SQL> select file#,status, CHECKPOINT_CHANGE# from v$datafile_header;
     FILE# STATUS  CHECKPOINT_CHANGE#
---------- ------- ------------------
         1 ONLINE              458551
         2 ONLINE              458551
         3 ONLINE              458551
         4 ONLINE              458551
         5 ONLINE              458551

以上部分证明：
1.online datafile也不触发database checkpoint
2.tablespace offline后v$datafile.enabled为DISABLED
3.控制文件对应表空间scn不再变化,datafile header scn变为0
4.tablespace online不需要recover

tablespace read only(READ ONLY)

SQL> alter tablespace users read only;
Tablespace altered.
SQL> select file#,ts#,CHECKPOINT_CHANGE#,enabled,status,name from v$datafile;
     FILE#        TS# CHECKPOINT_CHANGE# ENABLED    STATUS  NAME
---------- ---------- ------------------ ---------- ------- --------------------------------------------------
         1          0             458551 READ WRITE SYSTEM  /u01/oracle/oradata/XFF/system01.dbf
         2          1             458551 READ WRITE ONLINE  /u01/oracle/oradata/XFF/undotbs01.dbf
         3          2             458551 READ WRITE ONLINE  /u01/oracle/oradata/XFF/sysaux01.dbf
         4          4             458567 READ ONLY  ONLINE  /u01/oracle/oradata/XFF/users01.dbf
         5          4             458567 READ ONLY  ONLINE  /u01/oracle/oradata/XFF/users02.dbf
SQL> select file#,status, CHECKPOINT_CHANGE# from v$datafile_header;
     FILE# STATUS  CHECKPOINT_CHANGE#
---------- ------- ------------------
         1 ONLINE              458551
         2 ONLINE              458551
         3 ONLINE              458551
         4 ONLINE              458567
         5 ONLINE              458567
SQL> alter system checkpoint;
System altered.
SQL>  select file#,ts#,CHECKPOINT_CHANGE#,enabled,status,name from v$datafile;
     FILE#        TS# CHECKPOINT_CHANGE# ENABLED    STATUS  NAME
---------- ---------- ------------------ ---------- ------- --------------------------------------------------
         1          0             458581 READ WRITE SYSTEM  /u01/oracle/oradata/XFF/system01.dbf
         2          1             458581 READ WRITE ONLINE  /u01/oracle/oradata/XFF/undotbs01.dbf
         3          2             458581 READ WRITE ONLINE  /u01/oracle/oradata/XFF/sysaux01.dbf
         4          4             458567 READ ONLY  ONLINE  /u01/oracle/oradata/XFF/users01.dbf
         5          4             458567 READ ONLY  ONLINE  /u01/oracle/oradata/XFF/users02.dbf
SQL> select file#,status, CHECKPOINT_CHANGE# from v$datafile_header;
     FILE# STATUS  CHECKPOINT_CHANGE#
---------- ------- ------------------
         1 ONLINE              458581
         2 ONLINE              458581
         3 ONLINE              458581
         4 ONLINE              458567
         5 ONLINE              458567
SQL> alter tablespace users read write;
Tablespace altered.
SQL> select file#,ts#,CHECKPOINT_CHANGE#,enabled,status,name from v$datafile;
     FILE#        TS# CHECKPOINT_CHANGE# ENABLED    STATUS  NAME
---------- ---------- ------------------ ---------- ------- --------------------------------------------------
         1          0             458581 READ WRITE SYSTEM  /u01/oracle/oradata/XFF/system01.dbf
         2          1             458581 READ WRITE ONLINE  /u01/oracle/oradata/XFF/undotbs01.dbf
         3          2             458581 READ WRITE ONLINE  /u01/oracle/oradata/XFF/sysaux01.dbf
         4          4             458635 READ WRITE ONLINE  /u01/oracle/oradata/XFF/users01.dbf
         5          4             458635 READ WRITE ONLINE  /u01/oracle/oradata/XFF/users02.dbf
SQL> select file#,status, CHECKPOINT_CHANGE# from v$datafile_header;
     FILE# STATUS  CHECKPOINT_CHANGE#
---------- ------- ------------------
         1 ONLINE              458581
         2 ONLINE              458581
         3 ONLINE              458581
         4 ONLINE              458635
         5 ONLINE              458635
SQL> alter system checkpoint;
System altered.
SQL>  select file#,ts#,CHECKPOINT_CHANGE#,enabled,status,name from v$datafile;
     FILE#        TS# CHECKPOINT_CHANGE# ENABLED    STATUS  NAME
---------- ---------- ------------------ ---------- ------- --------------------------------------------------
         1          0             458649 READ WRITE SYSTEM  /u01/oracle/oradata/XFF/system01.dbf
         2          1             458649 READ WRITE ONLINE  /u01/oracle/oradata/XFF/undotbs01.dbf
         3          2             458649 READ WRITE ONLINE  /u01/oracle/oradata/XFF/sysaux01.dbf
         4          4             458649 READ WRITE ONLINE  /u01/oracle/oradata/XFF/users01.dbf
         5          4             458649 READ WRITE ONLINE  /u01/oracle/oradata/XFF/users02.dbf
SQL> select file#,status, CHECKPOINT_CHANGE# from v$datafile_header;
     FILE# STATUS  CHECKPOINT_CHANGE#
---------- ------- ------------------
         1 ONLINE              458649
         2 ONLINE              458649
         3 ONLINE              458649
         4 ONLINE              458649
         5 ONLINE              458649

以上部分证明：
1.tablespace read only 对应的v$datafile.enabled为READ ONLY
2.tablespace read only与tablespace read write之间的转换也不会触发database checkpoint

补充说明
官方文档给出来的v$datafile.enabled有以下几种
DISABLED – No SQL access allowed
READ ONLY – No SQL updates allowed
READ WRITE – Full access allowed
UNKNOWN – should not occur unless the control file is corrupted
但是对于UNKNOWN我通过模拟重建控制文件,缺少数据文件(为READ WRITE),通过在线删除数据文件(为READ WRITE),都不能出现UNKNOWN状态,如果知道的朋友请告知我.

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