Oracle SQL Developer – Cannot List Tables but Visible in PL/SQL Developer

Try this:

COTT3 = 
 (DESCRIPTION =
  (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))
  (CONNECT_DATA = 
   (SERVER = DEDICATED)
   (SERVICE_NAME = COTT3)
  )
)

If that doesn't work, replace "SERVICE_NAME" with "SID".

Put this in $ORACLE_HOME/network/admin/listener.ora:

LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS_LIST =
        (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))
      )
    )
  )

SID_LIST_LISTENER =
(SID_LIST =
    (SID_DESC =
      (SID_NAME = COTT3)
          (ORACLE_HOME = /opt/oracle/oracle/product/10.2.0/db_1 )
    )
  )

Then restart the listener with:

lsnrctl reload

Are you 100% sure that the database has started up?

Does:

ps auxww | grep pmon | grep -i cott3

... produce any output?

Sounds like the network buffer is being filled but not flushed. SQL*Net performance in this area is often managed by setting tcp.nodelay=yes in sqlnet.ora; also look at the send_buf_size and recv_buf_size parameters.

SQL*Dev working and not SQL*Plus are what pointed me to this type of troubleshooting approach. SQL*Developer uses jdbc behind the scenes to do its fetching.

hth!