昨天去某客户部署RMAN备份,在跑shell脚本的时候,提示找不到归档日志,因为客户那里之前只对数据库做EXPDP逻辑导出备份,并且每
-rw-r----- 1 oracle oinstall 606K Sep 24 12:00 ora10g-4175411955_20140924_859118422_297.arc
-rw-r----- 1 oracle oinstall 166M Sep 24 12:02 ora10g-4175411955_20140924_859118425_298.db
-rw-r----- 1 oracle oinstall 610K Sep 24 12:02 ora10g-4175411955_20140924_859118562_299.arc
-rw-r----- 1 oracle oinstall 7.3M Sep 24 12:02 ora10g-c-4175411955-20140924-01.ctl
可以看到,,备份全部完成了,共生成了2个归档日志备份集(arc),1个数据库备份集(db)以及控制文件备份集(ctl),这里有个细节要注意,由于我在脚本中写入了%s参数,从上面生成备份集生成的时间以及顺序可以发现RMAN备份这样一个顺序:
1. 对现有可以备份的数据库归档日志文件做一个备份
2. 对数据库进行备份
3. 切换一下日志,对完成全库备份后的归档日志再做一个备份(即使你没有通过RMAN> sql "alter system archive log current";来手动切)
4. 对控制文件备份(包括spfile,生成在同一个备份集)
我们可以看一下详细的日志输出,来对这个顺序有更深刻的了解:
Starting backup at 24-914
current log archived
using channel ORA_DISK_1
channel ORA_DISK_1: starting compressed archive log backupset
channel ORA_DISK_1: specifying archive log(s) in backup set
input archive log thread=1 sequence=11 recid=216 stamp=859118422
channel ORA_DISK_1: starting piece 1 at 24-914
channel ORA_DISK_1: finished piece 1 at 24-914
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:03
Finished backup at 24-914
Starting backup at 24-914
using channel ORA_DISK_1
channel ORA_DISK_1: starting compressed full datafile backupset
channel ORA_DISK_1: specifying datafile(s) in backupset
input datafile fno=00001 name=/u01/app/oracle/oradata/ora10g/system01.dbf
input datafile fno=00003 name=/u01/app/oracle/oradata/ora10g/sysaux01.dbf
input datafile fno=00002 name=/u01/app/oracle/oradata/ora10g/undotbs01.dbf
input datafile fno=00005 name=/u01/app/oracle/oradata/ora10g/example01.dbf
input datafile fno=00006 name=/u01/app/oracle/oradata/ora10g/zlm01.dbf
input datafile fno=00004 name=/u01/app/oracle/oradata/ora10g/users01.dbf
channel ORA_DISK_1: starting piece 1 at 24-914
channel ORA_DISK_1: finished piece 1 at 24-914
channel ORA_DISK_1: backup set complete, elapsed time: 00:02:16
Finished backup at 24-914
Starting backup at 24-914
current log archived
using channel ORA_DISK_1
channel ORA_DISK_1: starting compressed archive log backupset
channel ORA_DISK_1: specifying archive log(s) in backup set
input archive log thread=1 sequence=12 recid=217 stamp=859118561
channel ORA_DISK_1: starting piece 1 at 24-914
channel ORA_DISK_1: finished piece 1 at 24-914
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:02
Finished backup at 24-914
Starting Control File and SPFILE Autobackup at 24-914
Finished Control File and SPFILE Autobackup at 24-914

InnoDBBufferPool reduces disk I/O by caching data and indexing pages, improving database performance. Its working principle includes: 1. Data reading: Read data from BufferPool; 2. Data writing: After modifying the data, write to BufferPool and refresh it to disk regularly; 3. Cache management: Use the LRU algorithm to manage cache pages; 4. Reading mechanism: Load adjacent data pages in advance. By sizing the BufferPool and using multiple instances, database performance can be optimized.

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MySQL is suitable for beginners to learn database skills. 1. Install MySQL server and client tools. 2. Understand basic SQL queries, such as SELECT. 3. Master data operations: create tables, insert, update, and delete data. 4. Learn advanced skills: subquery and window functions. 5. Debugging and optimization: Check syntax, use indexes, avoid SELECT*, and use LIMIT.

MySQL efficiently manages structured data through table structure and SQL query, and implements inter-table relationships through foreign keys. 1. Define the data format and type when creating a table. 2. Use foreign keys to establish relationships between tables. 3. Improve performance through indexing and query optimization. 4. Regularly backup and monitor databases to ensure data security and performance optimization.

MySQL is an open source relational database management system that is widely used in Web development. Its key features include: 1. Supports multiple storage engines, such as InnoDB and MyISAM, suitable for different scenarios; 2. Provides master-slave replication functions to facilitate load balancing and data backup; 3. Improve query efficiency through query optimization and index use.

SQL is used to interact with MySQL database to realize data addition, deletion, modification, inspection and database design. 1) SQL performs data operations through SELECT, INSERT, UPDATE, DELETE statements; 2) Use CREATE, ALTER, DROP statements for database design and management; 3) Complex queries and data analysis are implemented through SQL to improve business decision-making efficiency.

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