Internals of Oracle's SQL*Net Oracle Tips by Burleson Consulting

The Data Warehouse Development Life Cycle

The Internals Of Oracle's SQL*Net

In its most basic form, SQL*Net is a software tool that allows a network of Oracle clients and servers to communicate transparently on top of any underlying network topology or protocol using SQL. Although SQL*Net is a very robust and sophisticated tool, you must appreciate the inherent complexity that goes along with the flexibility of SQL*Net. This section provides a no-nonsense overview of the SQL*Net architecture. All of the examples are based on Unix.

Due to its sophisticated architecture, it is not trivial to install SQL*Net on a client or server. For Unix systems, the following files are necessary to operate SQL*Net 2.0:

* etc/tnsnames.ora--Used for outgoing database requests, this file contains all of the database names (sids) running on the processor, as well as the domain name, protocol, host, and port information. When a new database is added to a box, you must update this file (changes to tnsnames.ora become effective instantly). Note that the SQL*Net version 1.0 file equivalent is etc/oratab.

* etc/listener.ora--This file contains a list of local databases for use by incoming connections. When you add a new destination database to a Unix host, you must also add it to this file.

* etc/hosts--This file lists all of your network addresses.

* etc/services--This file lists all of the SQL*Net services.

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This is an excerpt from "High Performance Data Warehousing", copyright 1997.

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