Tom,
I am confused while creating and using database link. So need you advise on that. I have two databases with following setting

LOCAL REMOTE
db_name mass orcl
db_domain world world
global_name true true

Now if I am creating a database link like

afm@MASS.WORLD> create database link orcl.world@albert connect to fsa identified by fsa using 'ASPECT.WORLD’;

Database link created.
In one of the thread so have said add some extra stuff after @, so i have added my server name.

afm@MASS.WORLD> select count(*) from em@orcl.WORLD@albert;
select count(*) from em@orcl.WORLD@albert
*
ERROR at line 1:
ORA-02085: database link ORCL.WORLD@ALBERT connects to ORACLE.WORLD

Why its trying to connect to ORACLE.WORLD?

But if alter the session for global_name it works

afm@MASS.WORLD> alter session set global_names=false;

Session altered.

afm@MASS.WORLD> select count(*) from em@orcl.WORLD;

COUNT(*)
----------
2852

Why I need to set the flag to FALSE, when I have created the DB link same as database name?

I thought if i have created DB link with Database name then global_name parametre is not relevant.

Thanks

Vivek

SQL> conn scott@unix
Enter password: *****
Connected.
SQL> select * from global_name;

GLOBAL_NAME
-------------------------------------------------------------------
RMLMYS

above is remote database global name

SQL> conn scott@rane
Enter password: *****
Connected.
SQL> select * from global_name;

GLOBAL_NAME
-------------------------------------------------------------------
ORACLE.WORLD

As you have said I have suggested above I used same name as global name

SQL> create database link RMLMYS@unixserver
  2  connect to scott
  3  identified by tiger
  4  using 'unix';

Database link created.

Then why this error

SQL> select * from dual@RMLMYS@unixserver;
select * from dual@RMLMYS@unixserver
                   *
ERROR at line 1:
ORA-02085: database link RMLMYS.WORLD@UNIXSERVER connects to RMLMYS

But after making false it is working fine 
Why I should make false
As you have suggested for vivek I have used Global name not db name

SQL> alter session set global_names=false
  2  /

Session altered.

SQL> select * from dual@RMLMYS@unixserver;

D
-
X 

great answer

https://asktom.oracle.com/pls/apex/f?p=100:11:0::::P11_QUESTION_ID:563222962265