續(xù) http://nvd11.blog.163.com/blog/static/20001831220127710369356/

五、數(shù)據(jù)文件

??? 數(shù)據(jù)文件是數(shù)據(jù)庫中最重要的一個(gè)要求，是所有的數(shù)據(jù)庫內(nèi)容存放的地方

??? datafile是按照表空間為組織單位，表空間的構(gòu)成是按照段區(qū)塊為層次－－－數(shù)據(jù)文件的邏輯結(jié)構(gòu)

??? datafile就是表空間的物理文件。

??? datafile中的內(nèi)容是通過dbwr把data buffer cache中的dirty buffer data 寫入的

??? dbwr觸發(fā)：

??? ??? ckpt觸發(fā)，dirty buffer 到一定量的時(shí)候，data buffer caceh 的內(nèi)存空間快用完了

?????? 查詢空閑內(nèi)存空間超時(shí)，表空間offline/read only,表的drop, truncate 開始執(zhí)備份表空間的時(shí)候 */

??????

??? --查看數(shù)據(jù)文件

??? SQL> select file# ,name,status,enabled,bytes/1024/1024 M from v$datafile;

?

?????? ?FILE# NAME?????????????????????????????????????????????? STATUS? ENABLED???????????? M

??? ---------- -------------------------------------------------- ------- ---------- ----------

?????????? ?1 /u01/app/oracle/oradata/orcl/system01.dbf????????? SYSTEM? READ WRITE??????? 490

?????????? ?2 /u01/app/oracle/oradata/orcl/undotbs01.dbf???????? ONLINE? READ WRITE???????? 30

?????????? ?3 /u01/app/oracle/oradata/orcl/sysaux01.dbf????????? ONLINE? READ WRITE??????? 250

?????????? ?4 /u01/app/oracle/oradata/orcl/users01.dbf?????????? ONLINE? READ WRITE????????? 5

?????????? ?5 /u01/app/oracle/oradata/orcl/example01.dbf???????? ONLINE? READ WRITE??????? 100

?????????? ?6 /u01/app/oracle/oradata/orcl/tbs1_1.dbf??????????? ONLINE? READ WRITE??????? 100

?????????? ?7 /u01/app/oracle/oradata/orcl/tbs1_2.dbf??????????? ONLINE? READ WRITE???????? 60

?????????? ?

??? SQL> select tablespace_name,file_name,user_bytes/1024/1024 M from dba_data_files;

?

??? TABLESPACE_NAME??????????????? FILE_NAME??????????????????????????????????????????????????????? M

??? ------------------------------ ------------------------------------------------------- ----------

??? USERS01??????????????????????? /u01/app/oracle/oradata/orcl/users01.dbf??????????????????? 4.9375

??? SYSAUX???????????????????????? /u01/app/oracle/oradata/orcl/sysaux01.dbf???????????????? 249.9375

??? UNDOTBS1?????????????????????? /u01/app/oracle/oradata/orcl/undotbs01.dbf???????????????? 29.9375

??? SYSTEM???????????????????????? /u01/app/oracle/oradata/orcl/system01.dbf???????????????? 489.9375

??? EXAMPLE??????? ????????????????/u01/app/oracle/oradata/orcl/example01.dbf???????????????? 99.9375

??? TBS1?????????????????????????? /u01/app/oracle/oradata/orcl/tbs1_1.dbf??????????????????? 99.9375

??? TBS1?????????????????????????? /u01/app/oracle/oradata/orcl/tbs1_2.dbf?? ?????????????????59.9375

?

??? --數(shù)據(jù)文件的增加與刪除

??? --為TBS1增加一個(gè)數(shù)據(jù)文件

??? SQL> alter tablespace tbs1 add datafile '/u01/app/oracle/oradata/orcl/tbs1_3.dbf' size 10m autoextend on;

??? --還有一種創(chuàng)建表空間時(shí)不指定大小，而是重用一個(gè)存在的dbf要用resue參數(shù)，reuse 是把原有的結(jié)構(gòu)拿來用，里面的數(shù)據(jù)是用不了的，因?yàn)樵缍紱]有了。

???

??? --刪表空間中的數(shù)據(jù)文件，g以后的版本才用以下功能，在之前版本的就只能把表空間給干掉。

??? SQL> alter tablespace tbs1 drop datafile '/u01/app/oracle/oradata/orcl/tbs1_3.dbf';

???

??? --有數(shù)據(jù)的數(shù)據(jù)文件不能刪。第一個(gè)不能刪，如果要?jiǎng)h就把表空間干掉，數(shù)據(jù)文件中有數(shù)據(jù)寫入的文件也不能刪除，如下

??? SQL> alter tablespace tbs1 drop datafile 7;? --7是v$datafile中的file#.

??? alter tablespace tbs1 drop datafile 7

??? *

??? ERROR at line 1:

??? ORA-03262: the file is non-empty

???

??? /*

??? 數(shù)據(jù)文件的日志記錄

?????? 只有temp表空間是nologing? 別的都是logging的

??????? 日志記錄的幾種模式???

?????? ??? nologin????????? 并不是不記錄日志而是記錄的很少

?????????? logging????????? 正常記錄日志信息

?????? ??? force logging??? 記錄的日志比logging還詳細(xì) 記錄信息非常多? 用于DG data guard 容災(zāi)的情況 */

??? SQL> select tablespace_name ,logging,force_logging from dba_tablespaces;

?

??? TABLESPACE_NAME??????????????? LOGGING?? FOR

??? ------------------------------ --------- ---

??? SYSTEM???????????????????????? LOGGING? ?NO

??? UNDOTBS1?????????????????????? LOGGING?? NO

??? SYSAUX???????????????????????? LOGGING?? NO

??? TEMP?????????????????????????? NOLOGGING NO

??? USERS01??????????????????????? LOGGING?? NO

??? EXAMPLE??????????????????????? NOLOGGING NO

??? TBS1????????????????????? ?????LOGGING?? NO

???

??? --修改表空間中日志文件記錄的方式

?????? SQL> alter tablespace tablespace_name nologging | logging | force logging;

???

??? SQL> alter tablespace example logging;

?

??? Tablespace altered.

?

??? SQL> alter tablespace tbs1 force logging;

?

??? Tablespace altered.

?

??? SQL> select tablespace_name ,logging,force_logging from dba_tablespaces;

?

??? TABLESPACE_NAME??????????????? LOGGING?? FOR

??? ------------------------------ --------- ---

??? SYSTEM???????????????????????? LOGGING?? NO

??? UNDOTBS1?????????????????????? LOGGING?? NO

??? SYSAUX???????????????????????? LOGGING?? NO

??? TEMP?????????????????????????? NOLOGGING NO

??? USERS01??????????????????????? LOGGING?? NO

??? EXAMPLE??????????????????????? LOGGING?? NO

??? TBS1?????????????????????????? LOGGING?? YES

???

??? /*

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