Re: TWO_TASKING

I had posted a reply on the oracle.misc board where I first say this and thought I would add it to the posts here since there are several and none of them mentioned two_task and single_task Oracle processing, but instead only mention the Unix environment variable.

From: Tansel Ozkan >>
I came across the term 'TWO_TASK' in a couple places. But I don't really have a good understanding. What is meant by two_tasking? <<

First there is in a UNIX environment a shell variable TWO_TASK that Oracle searches for to find the default connection string. If the variable does not
exist Oracle attempts a direct connection to the SID specified by ORACLE_SID,
if set. We set it to the sqlnet version 2 alias that is the same as the Oracle
sid, both local and remote, that we wish to connect to.

But what two_task usually refers to in the manuals has nothing to do with this,
but actually refers to how Oracle spawns processes to handle user requests.  On
most Unix systems the application process makes a connection to Oracle and Oracle spawns a background process that does all the Oracle work. This means
that the two processes have to talk to each other which is overhead. Oracle
does this because the Unix OS can not protect the Oracle code from being stomped on by the application code within one process.

Oracle provides a compile script to generate single-task versions of the sql
loader, import, and export utilities that run faster than the normal versions
on many platforms.

Under VMS the single-task mode is the default when Oracle is installed and the
user fore-ground process and the Oracle background process are one and the same. This is because VMS can protect the Oracle code from being damaged by
the application even when they are in one process.

I hope this answers your question. I seem to remember reading one or two pages
on this topic in (I think) the installation manual.

Mark Powell -- Oracle 7 Certified DBA
- The only advice that counts is the advice that you follow so follow your own
advice - Received on Tue Sep 01 1998 - 00:00:00 CDT