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【Oracle】 redo的写入与恢复原理

suqiansiyang | 2018-10-25 13:45:26 | 阅读(2270) | 评论(0)

1 那么oracle是如何通过哪几个方面来实现这个持久性的呢？1) memory 方面，为了实现更好的课伸缩性和高并发，oracle引入了redo buffer。理论上讲，尽可能的实现每次都将commit的block都flush到disk中。不过，很多时候，如果业务量很大，那么这个可能也是一个硬件拼镜，比如IO。2）避免介质失败，关于这点，主要是通过进...【阅读全文】

【Oracle】深入理解SCN号

suqiansiyang | 2018-10-15 10:08:57 | 阅读(5890) | 评论(0)

在oracle中存在很多种scn，但是，只有如下几种是我们比较关注的。commit scn/cleanout scndatabase scn/on disk scn/thread scn/datafile checkpoint scn/start scnoffline scn/online scnresetlogs scnstop scnlow/high scn下面我们通过实验来展示，描述上述几种scn：++++++commit scn/cleanout scnSQL> create t...【阅读全文】

【Oracle】 RAC中常见的问题及处理方式

weijun1235 | 2018-09-30 16:58:31 | 阅读(4090) | 评论(0)

1、Oracle rac 安装常见问题安装RAC需要注意的问题：主机名大写主机名有下划线，中划线主机操作系统包安装少操作系统少补丁主机防火墙打开主机内核参数没有更改主机操作系统的时间存储多路径软...【阅读全文】

【Oracle】 Oracle分区表管理

weijun1235 | 2018-09-27 21:42:05 | 阅读(2120) | 评论(0)

Oracle分区表管理--管理分区应对哪种表应用分区功能； 1.大于2GB的表; 2.含有1000万条记录以上的表，表中含有的数据越多，SQL操作的执行速度就会越慢; 3.将会含有大量数据的表; 4.强行拆分后可利于并行操作的表; &nb...【阅读全文】

【Oracle】表碎片整理时shrink和move的选择

weijun1235 | 2018-09-24 16:52:55 | 阅读(2200) | 评论(0)

一、表的占用空间大小释放原理背景：生产环境中，经常会遇到表由于数据不断插入，导致空间越来越大，由于前期配置问题，没有做分区或者其他优化，而且生产数据实时向表插入。要删除历史数据来释放空间。分析：（1）没做分区表：由于没有分区表，所以无法分块对表进行清理。（2）表实时插入数据，数据量大，要保留部...【阅读全文】

【Oracle】 2018年ocp最新题库：052新加的考试题整理-36

unix_5359 | 2018-08-08 11:48:19 | 阅读(1870) | 评论(0)

36、Which two are true about roles?A) A role can be granted a combination of system and object privileges and other roles.B) The CONNECT role Is granted automatically to a user when It Is created.C) Roles are owned by SYSTEM.D) The RESOURCE role Is granted the CREATE SESSION priv...【阅读全文】

【Oracle】 2018OCP 052最新考试题库及答案整理-35

unix_5359 | 2018-08-08 11:43:06 | 阅读(1730) | 评论(0)

35、Your database is using Automatic Memory Management.Which two SGA components must be managed manually?A) default buffer cacheB) redo log bufferC) large poolD) shared poolE) keep buffer poolAnswer:BE【阅读全文】

【Oracle】 OCP 052考试最新题库和答案整理-34

unix_5359 | 2018-08-03 14:07:03 | 阅读(1610) | 评论(0)

34、Which two can be backed up by using RMAN when a database Is open in ARCHIVELOG mode, so that media recovery can be performed If required?A) control filesB) password fileC) pfileD) online redo logsE) flashback logsF) data filesAnswer:AF【阅读全文】

【Oracle】 OCP认证052最新考试题和答案整理-33

unix_5359 | 2018-08-03 14:02:53 | 阅读(1230) | 评论(0)

33、Where Is backup metadata stored for use by Recovery Manager (RMAN)?A) In the control fileB) In the SYSAUX tablespaceC) in the SPFILED) in the SYSTEM tablespaceE) In the diagnostic destination fliesAnswer:A【阅读全文】

【Oracle】 ocp考试052题库变化，新考题及答案整理-32

unix_5359 | 2018-08-02 11:24:33 | 阅读(1110) | 评论(0)

32、 Examine these commands and their output:? SQL> SELECT * FROM emp;? ENO ENAME? ---- -----? 100 Adam? 101 Alan? SQL> INSERT INTO emp VALUES(102,'Ben");? 1 row created.? SQL> COMMIT;? Commit completed.? SQL> UPDATE emp SET ename='Bryan' WHERE eno...【阅读全文】

【Oracle】 ocp题库变了，052新题及答案整理-31题

unix_5359 | 2018-08-02 11:03:19 | 阅读(1650) | 评论(0)

31、Which two events always request the LGWR to write?A) when LGWR is notified by a server process that performs a Commit or ROLLBACKB) When PMON restarts a server processC) when DBWn writes dirty buffersD) when a log switch occursE) when a checkpoint occursAnswer:CD...【阅读全文】

【Oracle】 ocp题库变化，052最新考试题和答案整理-30

unix_5359 | 2018-08-01 13:52:02 | 阅读(1310) | 评论(0)

30、Which is true when a database instance is shut down?A. Only transactional and normal modes wait for all uncommitted transactions to commit or rollback and then close the database.B. Immediate, transactional, and normal modes all result in a checkpoint.C. Neither the immediate nor ...【阅读全文】

【Oracle】 2018OCP最新题库052新加考题及答案整理-27

unix_5359 | 2018-07-30 15:06:05 | 阅读(1650) | 评论(0)

27、Examine these facts about a database:1. USERS is the database default tablespace.2. USER1, USER2, AND USER3 have the CREATE SESSION privilege.3. They also have UNLIMITED QUOTA on the default tablespace USERS.4. They have no other privileges.Examine these commands:SQL> c...【阅读全文】

【Oracle】 OCP 052最新考试题库还有答案收集整理-26题

unix_5359 | 2018-07-30 14:35:05 | 阅读(1470) | 评论(0)

26、In which state can you back up a database in ARCHIVELOGMODE using RMAN?A. NOMOUNT, MOUNT, AND OPENB. NOMOUNT AND MOUNT ONLYC. OPEN ONLYD. MOUNT AND OPEN ONLYE. OPEN RESTRICTED ONLYCorrect Answer: D【阅读全文】

【Oracle】 OCP2018最新题库，052新题库及答案整理-25题

unix_5359 | 2018-07-27 15:19:27 | 阅读(1550) | 评论(0)

25、Which is true about logical and physical database structures? (Choose the best answer)A. An undo tablespace has a temp file instead of a data file.B. A segment can consist of extents of different sizes.C. A permanent tablespace can only contain tables segments and index segments....【阅读全文】

【Oracle】 OCP新题库，052新加的考试题及答案整理-24题

unix_5359 | 2018-07-27 15:00:21 | 阅读(1260) | 评论(0)

24、 YOUR DB_RECOVERY_FILE_DEST_SIZE Is 8G.Currently, 5G of the space Is used of which 4G consists of obsolete backups.You execute this command:SQL> ALTER SYSTEM SET db_recovery_file_dest_size=2G;What is the outcome?A) It changes DB_RECOVERY_FILE_DEST_SIZE to 5G.B) It chan...【阅读全文】

【Oracle】 OCP认证052考试，新加的考题还有答案整理-23题

unix_5359 | 2018-07-26 11:07:52 | 阅读(1030) | 评论(0)

23、Which two are true about data dictionary and dynamic performance views (v$ views)?A) All database users have access to ALL_* views.B) Data dictionary view output is subject to read consistency.C) The defining queries for Oracle supplied dynamic performance views are stored In the...【阅读全文】

【Oracle】 OCP题库更新，052新加的考试题及答案整理-22题

unix_5359 | 2018-07-26 10:46:09 | 阅读(890) | 评论(0)

22、You are planning a software installation for both Oracle Database 11g Release 1 and Release 2.You plan to have at lease one database for each release managed by Grid Infrastructure for a Standalone Server.Which three are true in this scenario?A) Oracle 11g Release 1 databases mus...【阅读全文】

【Oracle】 OCP认证考试052新加的考题及答案收集整理-21题

unix_5359 | 2018-07-25 11:36:05 | 阅读(970) | 评论(0)

21、Which two are true about roles?A) A role can be password-protected.B) A role can be granted to another role.C) Only one default role can be granted to a user.D) A role can be granted only multiple system privileges not multiple object privileges.E) A role can be created on...【阅读全文】

【Oracle】 OCP 052新加的考试题收集整理-第20题

unix_5359 | 2018-07-25 11:22:13 | 阅读(780) | 评论(0)

20、 Which is true about the SYSTEM and SYSAUX tablespaces?A) The SYSAUX tablespace can be made read-only but the SYSTEM tablespace cannot.B) Both tablespaces can be used for temporary storage if no temporary tablespace is defined.C) Only the SYSTEM tablespace contains data dictionar...【阅读全文】

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