RMAN备份恢复管理工具,1、 脱机备份(一致性备份 冷备份 在数据库没有打开情况下,控制文件里的SCN号与所有数据文件中的SCN号一
一、物理备份
1、 脱机备份(一致性备份 冷备份 在数据库没有打开情况下,,控制文件里的SCN号与所有数据文件中的SCN号一致, 只能恢复到备份点 但是如果有归档日志可以继续往下恢复)
2、 联机备份(必须在归档模式下,因为是联机备份所有系统改变号不一定都相同所以需要备份之后的所有日志完整)
二、数据库全备命令
RMAN> backup format '/home/Oracle/backup/%U' database plus archivelog;或
RMAN>backup database plus archivelog delete input; 注释:delete input 代表剪切归档日志
(“%U”代表生成唯一的文件名)
所有备份的数据文件、控制文件、spfile文件、归档日志都放到指定的位置
备注:
RMAN> backup database format '/home/oracle/backup/%U' plus archivelog;
所有备份的数据文件放到指定的位置 其它文件放到快速恢复区
RMAN> backup database plus archivelog format '/home/oracle/backup/%U';
归档日志放到指定的位置 其它文件放到快速恢复区
三、RMAN相关命令
删除2份以前的备份包括归档日志
RMAN>delete force noprompt obsolete redundancy 2; (建议保留3份)
删除1份以前的备份包括归档日志
RMAN>delete force noprompt obsolete;
列出所有数据文件的备份
RMAN>list backup of database;
列出那些备份中包含控制文件备份
RMAN>list backup of controlfile;
列出那些备份中包含参数文件备份
RMAN>list backup of spfile;
列出那些备份中包含归档日志备份
RMAN>list backup of archivelog;
四、用RMAN恢复归档数据库
完全恢复只能是数据文件损坏,其他文件都是完好的 才能做到完全恢复
Recover database 只能在MOUNT状态下执行
Recover datafile 1 可以在数据库open状态下执行
Recover tablespace 可以在数据库open状态下执行
五、不完全恢复的类型
基于日志序列号的恢复-----------------当前联机日志损坏的情况
基于时间的恢复--------------------------用户错误操作
基于系统改变号--------------------------用户错误操作
使用RMAN进行不完全恢复的步骤:
不能对一个文件进行不完全恢复,只能对整个数据库进行不完全恢复;

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InnoDB uses redologs and undologs to ensure data consistency and reliability. 1.redologs record data page modification to ensure crash recovery and transaction persistence. 2.undologs records the original data value and supports transaction rollback and MVCC.

Key metrics for EXPLAIN commands include type, key, rows, and Extra. 1) The type reflects the access type of the query. The higher the value, the higher the efficiency, such as const is better than ALL. 2) The key displays the index used, and NULL indicates no index. 3) rows estimates the number of scanned rows, affecting query performance. 4) Extra provides additional information, such as Usingfilesort prompts that it needs to be optimized.

Usingtemporary indicates that the need to create temporary tables in MySQL queries, which are commonly found in ORDERBY using DISTINCT, GROUPBY, or non-indexed columns. You can avoid the occurrence of indexes and rewrite queries and improve query performance. Specifically, when Usingtemporary appears in EXPLAIN output, it means that MySQL needs to create temporary tables to handle queries. This usually occurs when: 1) deduplication or grouping when using DISTINCT or GROUPBY; 2) sort when ORDERBY contains non-index columns; 3) use complex subquery or join operations. Optimization methods include: 1) ORDERBY and GROUPB


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