How to check database link info in Oracle

GV$DBLINK lists database links that are currently open in a session across the cluster. Useful for spotting leaked dblink connections, verifying transactions in flight over a link, or checking whether a heterogeneous services link is being used.

SET PAGESIZE 200 LINES 200
COL db_link FORMAT a19
SET LONG 999

SELECT db_link,
       owner_id,
       logged_on,
       heterogeneous,
       open_cursors,
       in_transaction,
       update_sent
FROM   gv$dblink
ORDER BY db_link;