oracle出现sga导致ORA-00821 ORA-00093报错解决办法

本问题在linux环境下，windows环境下类似。

问题描述：

在数据库操作时不小心修改了share_pool的大小，导致重启数据库无法正常启动，报错为：

 SQL>startup;
 ORA-: Specified value of sga_target 512M is too small, needs to be at least 804M
 SQL>startup nomount;
 ORA-: _shared_pool_reserved_min_alloc must be between  and
 SQL>show parameter sga
 NAME                                 TYPE        VALUE
 ------------------------------------ ----------- ------------------------------
 lock_sga                             boolean     FALSE
 pre_page_sga                         boolean     FALSE
 sga_max_size                         big integer 512M
 sga_target                           big integer 512M
 SQL> quit
 Disconnected from Oracle Database 11g Enterprise Edition Release 11.2.0.4. - 64bit Production
 With the Partitioning, OLAP, Data Mining and Real Application Testing options

原因分析及解决：

原因一定是不当的操作导致shared_pool_size为非正常值，只需要改回正常值（根据报错，大于804M即可）。

SQL>create pfile='/home/oracle/temp_init.ora' from spfile;
    注意：/home/oracle/这个目录需要oracle用户有读写权限才行
SQL>quit;

[oracle@dbs ~]$ cd /home/oracle/
[oracle@dbs ~]$ vi temp_init.ora

将标记处改为大于804M即可，这里改为900M

ORCL.__db_cache_size=
ORCL.__java_pool_size=
ORCL.__large_pool_size=
ORCL.__oracle_base='/home/oracle'#ORACLE_BASE set from environment
ORCL.__pga_aggregate_target=
ORCL.__sga_target=
ORCL.__shared_io_pool_size=
ORCL.__shared_pool_size=
ORCL.__streams_pool_size=
*.audit_file_dest='/home/oracle/admin/orcl/adump'
*.audit_trail='db'
*.compatible='11.2.0.4.0'
*.control_files='/home/oracle/oradata/orcl/control01.ctl','/home/oracle/fast_recovery_area/orcl/control02.ctl'
*.db_block_size=
*.db_domain=''
*.db_name='orcl'
*.db_recovery_file_dest='/home/oracle/fast_recovery_area'
*.db_recovery_file_dest_size=
*.diagnostic_dest='/home/oracle'
*.dispatchers='(PROTOCOL=TCP) (SERVICE=ORCLXDB)'
*.open_cursors=
*.pga_aggregate_target=
*.processes=
*.remote_login_passwordfile='EXCLUSIVE'
*.sessions=
*.sga_target=
*.undo_tablespace='UNDOTBS1'

然后强制加载pfile即可：

SQL> startup pfile='/home/oracle/temp_init.ora'
ORACLE instance started.

Total System Global Area  939495424 bytes
Fixed Size                  2258840 bytes
Variable Size             666896488 bytes
Database Buffers          260046848 bytes
Redo Buffers               10293248 bytes
Database mounted.
Database opened.
SQL> show parameter sga

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
lock_sga                             boolean     FALSE
pre_page_sga                         boolean     FALSE
sga_max_size                         big integer 900M
sga_target                           big integer 900M
SQL> quit
Disconnected from Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
[oracle@dbs ~]$

用PLSQL登录或者平台登录测试看，数据库已经正常了