The account should only have
the CREATE SESSION privilege; it should not have any privileges on any of the application tables.
If your application uses database links infrequently, you should use traditional database links
without the shared clause. Without the shared clause, each database link connection requires a
separate connection to the remote database. In general, use shared database links when the
number of users accessing a database link is expected to be much larger than the number of
server processes in the local database.
Managing Database Links
You can retrieve information about public database links via the DBA_DB_LINKS data dictionary
view. You can view private database links via the USER_DB_LINKS data dictionary view. Whenever
possible, separate your users among databases by application so that they may all share the same
public database links. As a side benefit, these users will usually also be able to share public grants
and synonyms.
The columns of the DBA_DB_LINKS data dictionary view are listed in the following table.
The password for the link to use is not viewable via DBA_DB_LINKS; it is encrypted in the SYS.
LINK$ table starting with Oracle Database 10g Release 2.
Column Name Description
OWNER The owner of the database link
DB_LINK The name of the database link (such as HR_LINK in this chapter??™s examples)
USERNAME The name of the account to use to open a session in the remote database if
a specific connection is used
HOST The connect string that will be used to connect to the remote database
CREATED The creation date for the database link
NOTE
The number of database links that can be used by a single query is
limited by the OPEN_LINKS parameter in the database??™s initialization
file.
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