Database Reference
In-Depth Information
In a few moments, you will learn how to generate a list of all undocumented parameters
along with the default value and a description for each. The documented V$ view
V$FIXED_
VIEW_DEFINITION
will serve as our starting point. This V$ view is the repository for all V$ and
GV$ views as well as X$ tables of an instance. Inquiring this view about
V$PARAMETER
gives
the following:
SQL> COLUMN view_definition FORMAT a80 WORD_WRAPPED
SQL> SELECT view_definition FROM v$fixed_view_definition
WHERE view_name='V$PARAMETER';
VIEW_DEFINITION
----------------------------------------------------------------------------
select NUM , NAME , TYPE , VALUE , DISPLAY_VALUE, ISDEFAULT ,
ISSES_MODIFIABLE, ISSYS_MODIFIABLE , ISINSTANCE_MODIFIABLE, ISMODIFIED,
ISADJUSTED, ISDEPRECATED, DESCRIPTION, UPDATE_COMMENT, HASH
from GV$PARAMETER where inst_id = USERENV('Instance')
We learn that
V$PARAMETER
is based on
GV$PARAMETER
and that the former removes the cross-
instance information found in the latter by filtering rows from other instances. No surprises here.
Except for the additional column
INST_ID
,
GV$PARAMETER
has the same structure as
V$PARAMETER
.
SQL> DESC gv$parameter
Name Null? Type
----------------------------------------- -------- -------------
INST_ID NUMBER
NUM NUMBER
NAME VARCHAR2(80)
TYPE NUMBER
VALUE VARCHAR2(512)
DISPLAY_VALUE VARCHAR2(512)
ISDEFAULT VARCHAR2(9)
ISSES_MODIFIABLE VARCHAR2(5)
ISSYS_MODIFIABLE VARCHAR2(9)
ISINSTANCE_MODIFIABLE VARCHAR2(5)
ISMODIFIED VARCHAR2(10)
ISADJUSTED VARCHAR2(5)
ISDEPRECATED VARCHAR2(5)
DESCRIPTION VARCHAR2(255)
UPDATE_COMMENT VARCHAR2(255)
HASH NUMBER
Further tapping
V$FIXED_VIEW_DEFINITION
gives this:
SQL> SELECT view_definition FROM v$fixed_view_definition
WHERE view_name='GV$PARAMETER';
VIEW_DEFINITION
