About

One session = One connection = One transaction (one user behind its screen)

For session variable, see Oracle Database - (Application) Context

Session Id

  • SESSIONID - The auditing session identifier. You cannot use this attribute in distributed SQL statements.
  • SID - The session ID.

You can get the current values for a session with the help of the userenv context.

Vsession

When the username is null, this is server activity not client activity. The program runs oracle.exe.