See Oracle-defined implicit Parameters

Use show parameter xx in sqlplus to view the Oracle-defined parameters, which are obtained by querying v $ parameter. In addition, some implicit parameters in Oracle cannot be directly queried through the show parameter method.

Let's check the execution plan of select * from v $ parameter.

SQL> set autotrace traceonly;

SQL> select * from v $ parameter;

Row 288 has been selected.

Execution Plan

The actual parameter is derived from two tables x $ ksppcv x $ ksppi.

Select x. ksppinm name, y. ksppstvl value, y. ksppstdf isdefault, decode (bitand (y. ksppstvf, 7), 1, 'modified', 4, 'System _ mod', 'false') ismod, decode (bitand (y. ksppstvf, 2), 2, 'true', 'false') isadj

From sys. x $ ksppi x, sys. x $ ksppcv y where x. inst_id = userenv ('instance') and

Y. inst_id = userenv ('instance') and x. indx = y. indx order

Translate (x. ksppinm ,'_','')

When modifying implicit parameters,

Alter system set "parameter_name" = value scope = both sid = '*';

Some of them can be modified in memory, while others can only be modified through spfile. Just try it and you will understand it.

Note that double quotation marks must be added. In addition, there must be no space in the quotation marks and only the parameter name can be included.