RE: processes vs sessions

Well, I can give you an example (in Unix anyway).

When Oracle starts up, it initiates several 'processes' - DBWR, LGWR,
PMON, SMON, - all background processes.  You'll see these in the
database as sessions without usernames.

In Dedicated server mode (vs. shared server), each new 'session' to the
db also gets 1 server 'process'.  Now that session can spawn additional
Oracle processes (parallel server for example), or perhaps autonomous
transactions (not sure if they get their own process or not).

On Windows, there is one Oracle process, and the process has multiple
threads.  I think the processes parameter limits the number of threads
the Oracle process can own.

Now, in Shared Server (formally MTS), each session does not equal one
process, as they are handled through the dispatcher and shared server
processes.

That's really just the surface, but I hope it helps.


Chris Taylor
Sr. Oracle DBA
Ingram Barge Company
Nashville, TN 37205
Office: 615-517-3355
Cell: 615-354-4799
Email: chris.taylor@xxxxxxxxxxxxxxx

-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Mir M. Mirhashimali
Sent: Tuesday, October 30, 2007 11:45 AM
To: oracle-l
Subject: processes vs sessions

Good morning,

can somebody explain what is the difference between Processes and 
Sessions init paramaters.

Thanks

-- 
Mir M. Mirhashimali
Oracle Systems Manager
Database Architecture, Enterprise Applications
Rice University
(713) 348 6365

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