Re: TWO_TASKING

From: Tansel Ozkan >>
I came accross 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 Mon Aug 31 1998 - 17:11:10 CDT