v$buffered_queues

SELECT QUEUE_SCHEMA,
       QUEUE_NAME,
       (NUM_MSGS - SPILL_MSGS) MEM_MSG,
       SPILL_MSGS,
       NUM_MSGS
  FROM V$BUFFERED_QUEUES
/

v$buffered_subscribers

This view displays information about the subscribers for all buffered queues in the instance. There is one row per subscriber per queue. If any object is replicated to more than one destination, there will be multiple subscribers to the same queue.

The following query shows the details of the subscribers:

select
'QUEUE_NAME         : ' ||  QUEUE_NAME        || chr(10) ||
'SUBSCRIBER_NAME    : ' ||  SUBSCRIBER_NAME   || chr(10) ||
'SUBSCRIBER_ADDRESS : ' ||  SUBSCRIBER_ADDRESS|| chr(10) ||
'SUBSCRIBER_TYPE    : ' ||  SUBSCRIBER_TYPE   || chr(10) ||
'STARTUP_TIME       : ' ||  STARTUP_TIME     || chr(10) ||
'LAST_BROWSED_SEQ   : ' ||  LAST_BROWSED_SEQ || chr(10) ||
'LAST_BROWSED_NUM   : ' ||  LAST_BROWSED_NUM  || chr(10) ||