oracle之参数文件探究(二)

eg：

SYS@orcl#select name,value from v$parameter where name='control_files';

NAME VALUE

-------------------- ------------------------------

control_files /opt/oracle/oradata/ORCL/contr

olfile/o1_mf_7q9c8orh_.ctl, /o

pt/oracle/flash_recovery_area/

ORCL/controlfile/o1_mf_7q9c8pc

f_.ctl

SYS@orcl#select name,value from v$parameter2 where name='control_files';

NAME VALUE

-------------------- ------------------------------

control_files /opt/oracle/oradata/ORCL/contr

olfile/o1_mf_7q9c8orh_.ctl

control_files /opt/oracle/flash_recovery_are

a/ORCL/controlfile/o1_mf_7q9c8

pcf_.ctl

SYS@orcl#

v$system_parameter2

该试图和v$system_parameter 的区别，与v$parameter和v$parameter2却别类似。

V$SYSTEM_PARAMETER2 displays information about the initialization parameters that are currently in effect for the instance, with each list parameter value appearing as a row in the view. A new session inherits parameter values from the instance-wide values.

Presenting the list parameter values in this format enables you to quickly determine the values for a list parameter. For example, if a parameter value is a, b, then the V$SYSTEM_PARAMETER view does not tell you if the parameter has two values (both a and b) or one value (a, b). V$SYSTEM_PARAMETER2 makes the distinction between the list parameter values clear.

理解了关于这几个试图的区别，那么我们在看一下，当我们查看参数文件中的摸一个参数的时候使用show parameter parameter_name命令，那么该命令查看了哪个试图呢？

eg：

SYS@orcl#alter session set sql_trace=true;

会话已更改。

SYS@orcl#show parameter processes;

NAME TYPE VALUE

------------------------------------ ------------------------------ ------------------------------

aq_tm_processes integer 0

db_writer_processes integer 1

gcs_server_processes integer 0

global_txn_processes integer 1

job_queue_processes integer 1000

log_archive_max_processes integer 4

processes integer 160

SYS@orcl#alter session set sql_trace=false;

会话已更改。

查看trace文件如下：

*** 2013-06-15 15:45:26.626

*** SESSION ID:(181.5) 2013-06-15 15:45:26.626

*** SERVICE NAME:(SYS$USERS) 2013-06-15 15:45:26.626

*** MODULE NAME:( Oracle Enterprise Manager.pin EM plsql) 2013-06-15 15:45:26.626

*** ACTION NAME:(start) 2013-06-15 15:45:26.626

PARSING IN CURSOR #19 len=32 dep=0 uid=0 oct=42 lid=0 tim=1371282326625892 hv=0 ad='2b1f0eaafc08' sqlid='0000000000000'

alter session set sql_trace=true

END OF STMT

EXEC #19:c=4001,e=312,p=0,cr=0,cu=0,mis=1,r=0,dep=0,og=1,tim=1371282326625880

*** 2013-06-15 15:45:35.418

=====================

PARSING IN CURSOR #16 len=289 dep=0 uid=0 oct=3 lid=0 tim=1371282335418064 hv=2462394820 ad='87d968b8' sqlid='7cfz5wy9caaf4'

SELECT NAME NAME_COL_PLUS_SHOW_PARAM,DECODE(TYPE,1,'boolean',2,'string