Query existing DBLinks

You can query information about existing DBLinks from views.

Procedure

After a DBLink is created, you can query the DBA_DB_LINKS, ALL_DB_LINKS, and USER_DB_LINKS views for information about created DBLinks.

SELECT * FROM SYS.USER_DB_LINKS;

The query result is as follows:

+-----------+----------+----------+-----------------+------------------+---------------------+-----------+--------+----------------+-------+-----------+-------------+---------------------+--------------+----------------------+--------------+--------------+------------------+
| DB_LINK   | USERNAME | PASSWORD | CREDENTIAL_NAME | CREDENTIAL_OWNER | HOST                | CREATED   | HIDDEN | SHARD_INTERNAL | VALID | INTRA_CDB | TENANT_NAME | REVERSE_TENANT_NAME | CLUSTER_NAME | REVERSE_CLUSTER_NAME | REVERSE_HOST | REVERSE_PORT | REVERSE_USERNAME |
+-----------+----------+----------+-----------------+------------------+---------------------+-----------+--------+----------------+-------+-----------+-------------+---------------------+--------------+----------------------+--------------+--------------+------------------+
| OB_DBLINK | SYS      |  NULL    | NULL            | NULL             | xx.xx.xx.xx:2881    | 22-MAY-23 | NULL   | NULL           | YES   | NULL      | oracle001   | NULL                | NULL         | NULL                 | 0.0.0.0      |            0 | NULL             |
+-----------+----------+----------+-----------------+------------------+---------------------+-----------+--------+----------------+-------+-----------+-------------+---------------------+--------------+----------------------+--------------+--------------+------------------+
1 row in set

The following describes the fields in the query results:

• DB_LINK: the name of the created DBLink.
• USERNAME: the username used by the DBLink to connect to the remote database.
• HOST: the hostname (IP address) of the remote database that the DBLink connects to.
• CREATED: the creation time of the DBLink.
• VALID: indicates whether the DBLink is available. This field is for compatibility only. The default value is YES.
• TENANT_NAME: the tenant name used by the DBLink to connect to the remote database.
• REVERSE_HOST: the hostname (IP address) of the local database that the reverse DBLink connects to. If the current DBLink does not support the reverse link feature, the value is 0.0.0.0.
• REVERSE_PORT: the port number of the local database that the reverse DBLink connects to. If the current DBLink does not support the reverse link feature, the value is 0.
• REVERSE_USERNAME: the username used by the reverse DBLink to connect to the local database. If the current DBLink does not support the reverse link feature, the value is NULL.

For more information about fields in the DBA_DB_LINKS, ALL_DB_LINKS, and USER_DB_LINKS views, see DBA_DB_LINKS, ALL_DB_LINKS, and USER_DB_LINKS.

References

For more information about operations on DBLinks, see the following topics:

• Create a DBLink

• Use a DBLink to access data in a remote database

• Use a DBLink to modify data in a remote database

• Drop a DBLink