Hidden Parameter

oracle initial parameters can be queryed from dynamic view:V$PARAMETER.
And this view are from two oracle internal dictionary tables: X$KSPPCV,X$KSPPI

SQL> select * from v$parameter;

259 rows selected.

Execution Plan
----------------------------------------------------------
Plan hash value: 1128103955

------------------------------------------------------------------------------
| Id  | Operation         | Name     | Rows  | Bytes | Cost (%CPU)| Time     |
------------------------------------------------------------------------------
|   0 | SELECT STATEMENT  |          |     1 |   926 |     1 (100)| 00:00:01 |
|*  1 |  HASH JOIN        |          |     1 |   926 |     1 (100)| 00:00:01 |
|*  2 |   FIXED TABLE FULL| X$KSPPI  |     1 |   249 |     0   (0)| 00:00:01 |
|   3 |   FIXED TABLE FULL| X$KSPPCV |   100 | 67700 |     0   (0)| 00:00:01 |
------------------------------------------------------------------------------

Predicate Information (identified by operation id):
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   1 - access("X"."INDX"="Y"."INDX")
       filter(TRANSLATE("KSPPINM",'_','#') NOT LIKE '#%' OR
              "KSPPSTDF"='FALSE' OR BITAND("KSPPSTVF",5)>0)
   2 - filter("X"."INST_ID"=USERENV('INSTANCE') AND
              TRANSLATE("KSPPINM",'_','#') NOT LIKE '##%')