Find internal of "show parameter" by session tracing

SQL> select * from v$version;

BANNER
--------------------------------------------
Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production
PL/SQL Release 11.2.0.3.0 - Production
CORE	11.2.0.3.0	Production
TNS for Linux: Version 11.2.0.3.0 - Production
NLSRTL Version 11.2.0.3.0 - Production

SQL> alter session set sql_trace=true;

Session altered.

SQL> oradebug setmypid
Statement processed.
SQL> show parameter optimizer

NAME				     TYPE	 VALUE
------------------------------------ ----------- ------------------------------
optimizer_capture_sql_plan_baselines boolean	 FALSE
optimizer_dynamic_sampling	     integer	 2
optimizer_features_enable	     string	 11.2.0.3
optimizer_index_caching 	     integer	 0
optimizer_index_cost_adj	     integer	 100
optimizer_mode			     string	 ALL_ROWS
optimizer_secure_view_merging	     boolean	 TRUE
optimizer_use_invisible_indexes      boolean	 FALSE
optimizer_use_pending_statistics     boolean	 FALSE
optimizer_use_sql_plan_baselines     boolean	 TRUE
SQL> oradebug tracefile_name
/u01/app/oracle/diag/rdbms/zhongwc/zhongwc/trace/zhongwc_ora_32320.trc

It's clear that "show parameter" actually make query on view v$parameter. 

SELECT NAME NAME_COL_PLUS_SHOW_PARAM,
       DECODE(TYPE,
              1,
              'boolean',
              2,
              'string',
              3,
              'integer',
              4,
              'file',
              5,
              'number',
              6,
              'big integer',
              'unknown') TYPE,
       DISPLAY_VALUE VALUE_CL_PLUS_SHOW_PARAM
  FROM V$PARAMETER
 WHERE UPPER(NAME) LIKE UPPER('%optimizer%')
 ORDER BY NAME_COL_PLUS_SHOW_PARAM, ROWNUM;

SQL> SELECT view_definition FROM v$fixed_view_definition WHERE view_name = 'V$PARAMETER';

VIEW_DEFINITION
----------------------------------------------------------------
select	NUM , NAME , TYPE , VALUE , DISPLAY_VALUE, ISDEFAULT , ISSES_MODIFIABLE , ISSYS_MODIFIABLE ,
 ISINSTANCE_MODIFIABLE, ISMODIFIED , ISADJUSTED , ISDEPRECATED, ISBASIC, DESCRIPTION, UPDATE_COMMENT
, HASH	from GV$PARAMETER where inst_id = USERENV('Instance')

hidden init parameters start with character '_' 

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