Grant SELECT on V$ Views

February 7, 2017

in DBA, exceptions, ORA errors, sql, views

Grant Select on V$ Views
When querying v$instance or v$session[1] as a non-admin user, you might come across this error:

SQL> select version
  2  from v$instance;
from v$instance
     *
ERROR at line 2:
ORA-00942: table or view does not exist

The error suggests that the non-admin user does not have the SELECT privilege on the sys-owned v$ view. On the face of it, the fix appears as simple as logging in as sys and granting select on the v$ view to the user.

Appearances are deceptive, they say. Try that and you will get an ORA-02030 error.

ORA-02030: can only select from fixed tables/views

SQL> grant select on v$instance
  2  to hr;
grant select on v$instance
                *
ERROR at line 1:
ORA-02030: can only select from fixed tables/views

What is ORA-02030?

The error ORA-02030 comes up when an attempt is made to select from a database object that is not a table or view.

Is that the case here? Is v$instance not a table or view? Let’s find out:

SQL> select object_name
  2       , owner
  3       , object_type
  4  from all_objects
  5  where object_name like 'V$INSTANCE';

OBJECT_NAME     OWNER    OBJECT_TYPE
--------------- -------- ----------------
V$INSTANCE      PUBLIC   SYNONYM

So…v$instance is a SYNONYM. It is not – as ORA-02030 rightly pointed out – a table or view.

How to resolve ORA-02030

ORA-02030 can be eliminated by granting select on the underlying table/view of the v$ synonym.

To find the underlying table/view, query all_synonyms:

SQL> select table_owner
  2       , table_name
  3  from all_synonyms
  4  where synonym_name like 'V$INSTANCE';

TABLE_OWNER                    TABLE_NAME
------------------------------ -----------
SYS                            V_$INSTANCE

That’s it – synonym v$instance points to an object with a slightly different name: v_$instance.

The column table_name in all_synonyms is something of a misnomer. It is called table_name all right, but it need not always hold a table. The column table_name in all_synonyms can be any database object for which a synonym may be defined – view, sequence, etc.  [Whoever wrote the story of A Table Is A Table would probably be astonished to see how close reality is to fiction.]

v_$instance is, indeed, not a table but a view:

SQL> select object_type
  2  from all_objects
  3  where object_name = 'V_$INSTANCE';

OBJECT_TYPE
-------------------
VIEW

Given these findings, all that’s needed is to grant select to the non-admin user on the v_$ view corresponding to the v$ synonym.

SQL> grant select on v_$instance
  2  to hr;

Grant succeeded.

Grant SUCCEEDED! Try selecting from V$ again…

Login as the non-admin user and retry the SQL that had failed earlier.

SQL> select version
  2  from v$instance;

VERSION
-----------------
11.2.0.2.0

It works.

Footnote: More about V$ views

[1] v$instance, v$session and other such v$ views are called dynamic performance views. They are continuously updated while a database is in use, and their contents relate primarily to performance.

These views provide data on internal disk/memory structures. You can select from v$ views, but you cannot update or alter them.

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