Oracle Tips  by Burleson Consulting

The Data Warehouse Development Life Cycle

Distributed Oracle Data Warehouses

Miscellaneous Management Tips For SQL*Net
It is possible to run two listeners simultaneously, one for version 1.0 and another listener for version 2.0. If a version 1.0 connect string is sent, a version 1.0 listener (tcpctl) will be used. Conversely, if a TNS connect description is sent, the version 2.0 listener (lsnrctl) will be used. A connect description is the name of a database (such as @mydata), which maps to the tnsnames.ora on the sending side and listener.ora on the receiving side.

It is essential to note that the functions of the ORACLE_SID and TWO_TASK variables have changed between SQL*Net version 1 and SQL*Net version 2. To use the MTS while you are local to the database, you should unset the ORACLE_SID variable and set the TWO_TASK to the SID name (EXPORT TWO_TASK=mydb). If the ORACLE_SID is active, you will still be able to connect--although you will not be able to take advantage of the MTS. You must change all login scripts and ORACLE_HOME/bin/oraenv files to reflect this new functionality.

We now have three ways to establish distributed database communications with MTS. We can choose from a shared service-name (sqlplus /@ram2db) or a dedicated service name (sqlplus /@d_ram2db--prefixing the SID with d_ will direct the listener to spawn a dedicated process for your program). And, we can also use a (TWO_TASK) server connect string (sqlplus /@t:host:sid). This latter approach will bypass the MTS and use a dedicated process.

If you like Oracle tuning, you may enjoy the book Oracle Tuning: The Definitive Reference , with over 900 pages of BC's favorite tuning tips & scripts.  You can buy it directly from the publisher and save 30%, and get instant access to the code depot of Oracle tuning scripts.