v$buffered_publishers

SELECT SENDER_NAME,
       SENDER_ADDRESS,
       QUEUE_NAME,       
       CNUM_MSGS,
       LAST_ENQUEUED_MSG
  FROM V$BUFFERED_PUBLISHERS
/

In the above statement, sender_name shows the Capture Process and the sender_address shows source database

v$buffered_queues

This view displays information about all buffered queues in the instance. There is one row per queue. It shows statistics such as LCR in memory and spilled LCRs. The user’s goal should be to control spilled LCRs. Spilled LCR events are written in a physical table where they may have performance impact on Streams processing

COLUMN QUEUE_SCHEMA HEADING 'Queue Owner' FORMAT A15
COLUMN QUEUE_NAME HEADING 'Queue Name' FORMAT A15
COLUMN MEM_MSG HEADING 'LCRs in Memory' FORMAT 99999999
COLUMN SPILL_MSGS HEADING 'Spilled LCRs' FORMAT 99999999
COLUMN NUM_MSGS HEADING 'Total Captured LCRs|in Buffered Queue' FORMAT 99999999