I want to know if the V$SESSION history is stored in any table to find out who logged into the database in the past. If not, then how can I find out who logged in the database in the past? Thanks in advance.
V$SESSION just logs the current sessions, I do not think there is any archival of this info ... for the future, you can create a system trigger to monitor who logs on and off, and store the result in a table
if you are on 8i you can use the system trigger, so that when ever someone loggs into the system he will be registerd.
befor you think about it, do not attempt to write a trigger on the source tables of v$session to create an arc table based on that.