How does "describe" work (difficult)

I know how one could write a "describe" command by querying the data dictionary, but recently I made a strange observation:

I turned on sqltrace, ran a "describe" command and turned sqltrace back off. The trace file showed the "trace on" and "trace off" commands but the "describe" command itself literally left no trace at all.

How could sqlplus possibly implement a describe command without causing an sqltrace ? Also it is amazingly fast, even when you describe a table at the other end of a database link which is aliased by a synonym.

I also ran "strace sqlplus". This showed a socked write and a socked read. This is no surprise, all commands basically look like like this (not just describe). I believe this is just classic SQL*Net communication. I don't know WHAT it writes though. Received on Sat Dec 22 2001 - 12:20:38 CST