一：Oracle 数据库实例简介
1：数据库实例的启动顺序：
使用数据库其实就是访问内存。即：数据库实例。数据库的启动是顺序是 先 nomount ----> mount -----> open.
2：数据库文件为：数据文件、控制文件、日志文件
数据库就是磁盘上的一些物理文件。可以利用 v$datafile 视图进行查看。如“/u01/app/oracle/oradata/orcl/system01.dbf”该路径下的“system01.dbf”被称作数据文件。数据库的数据信息都是存放在类似“*.dbf”的文件下。
1 [oracle@localhost ~]$ sqlplus / as sysdba; 2 3 SQL*Plus: Release 11.2.0.3.0 Production on Tue Apr 17 22:58:17 2018 4 5 Copyright (c) 1982, 2011, Oracle. All rights reserved. 6 7 8 Connected to: 9 Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - Production 10 With the Partitioning, OLAP, Data Mining and Real Application Testing options 11 12 SYS@orcl> select name from v$datafile; 13 14 NAME 15 -------------------------------------------------------------------------------- 16 /u01/app/oracle/oradata/orcl/system01.dbf 17 /u01/app/oracle/oradata/orcl/sysaux01.dbf 18 /u01/app/oracle/oradata/orcl/undotbs01.dbf 19 /u01/app/oracle/oradata/orcl/users01.dbf 20 /u01/app/oracle/oradata/orcl/example01.dbf 21 /u01/app/oracle/oradata/orcl/datafile1.dbf 22 /u01/app/oracle/oradata/orcl/ts1.dbf 23 /u01/app/oracle/oradata/orcl/datafile3.dbf 24 /u01/app/oracle/oradata/orcl/datafile4.dbf 25 /u01/app/oracle/oradata/orcl/datafile5.dbf 26 /u01/app/oracle/oradata/orcl/datafilebig_1.dfb 27 28 NAME 29 -------------------------------------------------------------------------------- 30 /u01/app/oracle/oradata/orcl/ts2.dbf 31 /u01/app/oracle/oradata/orcl/ts3.dbf 32 /u01/app/oracle/oradata/orcl/tbsp_1.dbf 33 34 14 rows selected. 35 36 SYS@orcl>再者从视图V$CONTROLFILE查看数据库的控制文件。"/u01/app/oracle/oradata/orcl/control01.ctl " 的“orcl”的目录是数据库实例名。
1 SYS@orcl> select name from v$controlfile; 2 3 NAME 4 -------------------------------------------------------------------------------- 5 /u01/app/oracle/oradata/orcl/control01.ctl 6 /u01/app/oracle/fast_recovery_area/orcl/control02.ctl 7 /u01/app/oracle/fast_recovery_area/orcl/control03.ctl 8 9 SYS@orcl>查看日志文件信息
1 SYS@orcl> select member from v$logfile; 2 3 MEMBER 4 -------------------------------------------------------------------------------- 5 /u01/app/oracle/oradata/orcl/redo03.log 6 /u01/app/oracle/oradata/orcl/redo02.log 7 /u01/app/oracle/oradata/orcl/redo01.log 8 /home/oracle/oracle_system_files_back/logfile_bak/logfile_bak_20180228/redo20180 9 228.log 10 11 /home/oracle/oracle_system_files_back/logfile_bak/logfile_bak_20180228/redo20180 12 228_1.log 13 14 /home/oracle/oracle_system_files_back/logfile_bak/logfile_bak_20180228/redo04.lo 15 g 16 17 MEMBER 18 -------------------------------------------------------------------------------- 19 20 21 6 rows selected. 22 23 SYS@orcl>
1：Oracle 实例结构
用户 通过访问数据库实例中的数据块来读取数据文件中的数据信息。用户不能直接读取数据文件中的数据信息。
数据库进程：
- 客户端进程
- Oracle服务器端进程
- 服务器进程
- 后台进程
当有客户端进程链接到Oracle数据库的时候，Oracle服务器会相应的给与分配一个服务器进程来与之匹配。然后通过服务器进程来访问获取数据库实例的数据信息。当服务器进程终止的时候，数据库实例还是可以在运行的。数据库实例是有数据库服务器的内存和数据库后台进程组成的。所以，服务器进程终止了，并不影响数据库实例的。
2：数据库实例配置
集群的作用：
- 保障数据库实例可以正常运行
- 确保负载均衡
切换数据库实例ID：
当 $ORACLE_SID 的值为那个 oracle实例名；则通过“sqlplus / as sysdba;”进行访问的数据库实例就是显示的那个。
3：Oracle 系统标识符（SID）
1 [oracle@localhost dbs]$ echo $ORACLE_SID 2 orcl 3 [oracle@localhost dbs]$ export ORACLE_SID=orcl 4 [oracle@localhost dbs]$ echo $ORACLE_SID 5 orcl 6 [oracle@localhost dbs]$ cd $ORACLE_HOME/dbs 7 [oracle@localhost dbs]$ pwd 8 /u01/app/oracle/product/11.2.0/db_1/dbs 9 [oracle@localhost dbs]$ ls 10 dbsorapwPROD1 hc_orcl.dat hc_PROD1.dat init.ora initorcl.ora initPROD1.ora lkORCL lkPROD1 orapworcl spfileorcl.ora spfilePROD1.ora 11 [oracle@localhost dbs]$
二：实例启动和关闭概述
1：实例和数据库启动概述
1 [oracle@localhost dbs]$ sqlplus / as sysdba; 2 3 SQL*Plus: Release 11.2.0.3.0 Production on Wed Apr 18 00:28:18 2018 4 5 Copyright (c) 1982, 2011, Oracle. All rights reserved. 6 7 8 Connected to: 9 Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - Production 10 With the Partitioning, OLAP, Data Mining and Real Application Testing options 11 12 SYS@orcl> show user 13 USER is "SYS" 14 SYS@orcl> 15
2：实例是如何启动的？
注：创建数据库是指：以命令的方式创建数据库。
3：数据库是如何装载的？
注：数据库恢复的操作有：热备恢复、冷备恢复
4：数据库是如何打开的？
5：数据文件检查
6：只读模式
注：切换数据库为只读模式：
1 2 SYS@orcl> shutdown immediate; 3 Database closed. 4 Database dismounted. 5 ORACLE instance shut down. 6 SYS@orcl> startup; 7 ORA-32004: obsolete or deprecated parameter(s) specified for RDBMS instance 8 ORACLE instance started. 9 10 Total System Global Area 1221992448 bytes 11 Fixed Size 1344596 bytes 12 Variable Size 939527084 bytes 13 Database Buffers 268435456 bytes 14 Redo Buffers 12685312 bytes 15 Database mounted. 16 Database opened. 17 SYS@orcl> select open_mode from v$database ; 18 19 OPEN_MODE 20 -------------------- 21 READ WRITE 22 23 SYS@orcl> shutdown immediate; 24 Database closed. 25 Database dismounted. 26 ORACLE instance shut down. 27 SYS@orcl> startup open read only; 28 ORA-32004: obsolete or deprecated parameter(s) specified for RDBMS instance 29 ORACLE instance started. 30 31 Total System Global Area 1221992448 bytes 32 Fixed Size 1344596 bytes 33 Variable Size 939527084 bytes 34 Database Buffers 268435456 bytes 35 Redo Buffers 12685312 bytes 36 Database mounted. 37 Database opened. 38 39 SYS@orcl> select open_mode from v$database ; 40 41 OPEN_MODE 42 -------------------- 43 READ ONLY 44 45 SYS@orcl> shutdown immediate; 46 Database closed. 47 Database dismounted. 48 ORACLE instance shut down. 49 SYS@orcl> startup mount; 50 ORA-32004: obsolete or deprecated parameter(s) specified for RDBMS instance 51 ORACLE instance started. 52 53 Total System Global Area 1221992448 bytes 54 Fixed Size 1344596 bytes 55 Variable Size 939527084 bytes 56 Database Buffers 268435456 bytes 57 Redo Buffers 12685312 bytes 58 Database mounted. 59 SYS@orcl> alter database open read only; 60 61 Database altered. 62 63 SYS@orcl> select open_mode from v$database ; 64 65 OPEN_MODE 66 -------------------- 67 READ ONLY 68 69 SYS@orcl>
7：限制模式打开数据库(RESTAICT)
8：数据库和实例关闭概述
shutdown abort
shutdown immediate
shutdown normal
9：数据库是如何关闭的
10：数据库是如何卸载的
11：数据库实例是如何关闭的
三：检查点概述
1：检查点的目的
2：Oracle 数据库何时启动检查点
1：线程检查点
2：表空间和数据文件的检查点
3：增量检查点
