Its default value is 4.
The managerial tasks involved for database links depend on the level to which you have
implemented location transparency in your databases. In the best-case scenario, connected user
links are used with service names or aliases; minimal link management in this scenario requires
610 Oracle Database 11g DBA Handbook
a consistent tnsnames.ora file among all hosts in the domain (or all hosts using the same LDAP
server for name resolution) and that user account/password combinations are the same within
the domain.
Synchronizing account/password combinations across databases may be difficult, but there
are several alternatives. First, you may force all changes to user account passwords to go through
a central authority. This central authority would have the responsibility for updating the password
for the account in all databases in the network??”a time-consuming but valuable task.
Second, you may audit user password changes made via the alter user command by auditing
the usage of that command (see Chapter 9). If a user??™s password changes in one database, it must
be changed on all databases available in the network that are accessed via connected user links.
If any part of the global object name??”such as a username??”is embedded in the database link,
a change affecting that part of the global object name requires that the database link be dropped
and re-created. For example, if the HR user??™s password were changed, the HR_LINK database link
with a specific connection defined earlier would be dropped with
drop database link HR_LINK;
and the link would have to be re-created using the new account password:
create public database link HR_LINK
connect to HR identified by employeeservices404
using 'hq';
You cannot create a database link in another user??™s account.
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