Help with a database link?

Question

Hiya
In our environment we have two servers for live and two for test. LIVE01 has db links to all other servers and they all work fine. I cannot get the db links up on test and I'm not sure why..
Both systems have global_names set FALSE so i can name the link anything I want. Both systems have identical TNSNAMES files and no SQLNET.ORA
The test systems have database names that do not have a suffice (it's the only significant difference I can find)
LIVE01 =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = 10.0.0.1)(PORT = 1521))
    (CONNECT_DATA =
      (SERVICE_NAME = LIVE01.MYDOMAIN.COM)
LIVE02 =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = 10.0.0.1)(PORT = 1521))
    (CONNECT_DATA =
      (SERVICE_NAME = LIVE02.MYDOMAIN.COM)
TEST01 =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = 10.0.0.2)(PORT = 1521))
    (CONNECT_DATA =
      (SERVICE_NAME = TEST01)
TEST02 =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = 10.0.0.2)(PORT = 1521))
    (CONNECT_DATA =
      (SERVICE_NAME = TEST02)
  )I've connected via RDP to each server, and I can tnsping and sqlplus user/pass@tnsname successfully on both servers, to all instances
The command I use in sqlplus to create the link on LIVE01:
CREATE PUBLIC DATABASE LINK live2dblink CONNECT TO user IDENTIFIED BY pass USING 'LIVE02';
CREATE PUBLIC DATABASE LINK test1dblink CONNECT TO user IDENTIFIED BY pass USING 'TEST01';
CREATE PUBLIC DATABASE LINK test2dblink CONNECT TO user IDENTIFIED BY pass USING 'TEST02';
SELECT * FROM ALL_DB_LINKS
PUBLIC     live2dblink.DOMAIN.COM     USER     LIVE02     2011-04-10 01:26:23
PUBLIC     test1dblink.DOMAIN.COM     USER     TEST01     2011-04-10 01:26:23
PUBLIC     test2dblink.DOMAIN.COM     USER     TEST02     2011-04-10 01:26:23SELECT * FROM DUAL@test2dblink ;
DUMMY
XBut if I repeat the relevant parts of the setup on test01 to link to the other 3 databases:
CREATE PUBLIC DATABASE LINK live1dblink CONNECT TO user IDENTIFIED BY pass USING 'LIVE01';
CREATE PUBLIC DATABASE LINK live2dblink CONNECT TO user IDENTIFIED BY pass USING 'LIVE02';
CREATE PUBLIC DATABASE LINK test2dblink CONNECT TO user IDENTIFIED BY pass USING 'TEST02';
SELECT * FROM ALL_DB_LINKS
PUBLIC     live1dblink.DOMAIN.COM     USER     LIVE01     2011-04-10 01:26:23
PUBLIC     live2dblink .DOMAIN.COM     USER     LIVE02     2011-04-10 01:26:23
PUBLIC     test2dblink.DOMAIN.COM     USER     TEST02     2011-04-10 01:26:23SELECT * FROM dual@test2dblink
error: "tns could not resolve service name"
I've run out of other things to check - it's not the "global names must match" issue because that's set false and verified with
SELECT name, value
FROM gv$parameter
WHERE (name LIKE '%link%')
OR (name IN ('global_names', 'dblink_encrypt_login'));
Yep, it's false..
I've seen other errors during my fiddling with various parameters, including "end of file on communication channel" when select * from dual@db_link.. as though the test instance kicked the connection from live but for the past half hour, this "cannot resolve" has been the persistent one..

Answer 1

Try using the full connect string in the database link like this:
CREATE PUBLIC DATABASE LINK test2dblink CONNECT TO user IDENTIFIED BY pass
USING '(description=(address=(protocol=tcp)(port=1521)(host=10.0.0.2))(connect_data=(sid=TEST02)))';