ABSTRACT
One of the most challenging tasks for an Oracle DBA is to keep an eye on sessions. Standard Oracle tools aimed at solving this problem are rather heavyweighted, and it is not that easy to deploy and customize these tools for particular DBA needs. It is good practice for a DBA to write scripts for sessions monitoring. Sometimes there can be a situation when graphical tools like Top Sessions Monitor cannot be used; all that is left for a DBA may be just a UNIX command console. More importantly, when writing these scripts, the DBA gets a clear understanding of how to work with the Oracle dictionary structures responsible for storing vital sessions information — what resources are allocated for a session, what types of locks are being used, etc. Also, the DBA will become aware of major problems with user sessions and possible workarounds for these problems.
