Can't return data from SQL/Plus and Toad but can from SQL Developer This one has me stumped. We are running an Oracle 11g on Amazon EC2 and I can connect and query fine with SQL Developer but with Toad and SQL/Plus I can connect but when I try to do a simple select out of v$session for example it gives me an ORA-03135 after a while. Here is what I have looked at/tried so far (in no particular order):


Looking in the listener.log file and seeing that all three connect fine
Turning the windows firewall completely off on the server (nothing changed)
TNSPing from my machine resolves
Port scanned to make sure port 1521 was open
Used telnet to make sure 1521 was open 
Compared listener setup to oracle db on another project
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!