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O/S level authentication in Oracle DBA

O/S level authentication

SYS> !

[dba12 dbs] $ vi initrajpar.ora



[dba12 dbs] $ exit

SYS> startup force  à includes shut abort & startup
[just like restart]
{not suggestible command}

SYS> sho parameter OS_authent_prefix

SYS> create usr raj6x71A identified externally;

The user should have os level authentication.

SYS> grant connect, resource to raj6x 71A;

SYS> !

[dba12 ~] $ pwd


[dba12 ~] $ sqlplus

SQL > sho user raj6x 71A


To create password file

[db a 12 dbs] $ vi initrajpor.ora

Remote-login_password file= exclusive


[dba12 dbs] $ orapwd file = orapw $ ORACLE_SID password= diamond

[dba12 dbs] $ cd

[dba12 ~] $ exit

SYS> startup force

SYS> sho parameter remote_login



SYS> select * from v$ pwfile_users

Now SYS can grant SYSDBA privileges to any other user.

SYS> grant sysdba to usr1;

SYS> startup force

SYS> conn user 1/user1 as sysdba

User1> startup force

SQL> sho user user1



ROL =s:

SYS> select * from session _ privs;

SYS> create role pay-1;

SYS> grant create tablespsce, create user to pay-1;

SYS> grant pay-1 to suer – 1;



(views related to roles)







  1. One segment can only be created in one table space
  2. One table space can have multiple segments.
  • One segment is made up of one or more extents.
  1. One extent is made up of COB.[contiguous oracle blocks]
  • One segment can have its multiple extents in the same or different data files provided these data files belongs to the same table space.
  • When a segment’s extents are completely filled up, ORACLE offers another extent to support the srowth of the segments on its own. This is known as DSA [dynamic space allocation] which is limited the free space available in the tablespace.









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