Oracle 8 Tips
by Burleson Consulting
The Data Warehouse Development Life Cycle
SQL*Net For Oracle Distributed Data Warehouses
SQL*Net can establish database communications in three ways: remote
connection, remote request, or distributed request. A remote
connection is the easiest way to make a database connection. The
sending database simply makes a request by specifying a table name
suffixed by @. SQL*Net takes it from there, seamlessly accessing the
remote database and returning the data to the initiating system.
Communication is established by making a distributed request to a
remote database. Within Oracle, @ specifies the remote database
name, but the functionality of the @ operator depends upon where it
is used. Here’s an example:
SELECT COUNT(*) FROM EMPLOYEE;
In this request, Scott is using Oracle SQL*Plus SQL command line
interface to connect to the London database, and @london is the
service name, as defined in the tnsnames.ora file. SQL*Net
recognizes this as a remote connection and determines the
appropriate linkage to establish communications with London.
Internally, Oracle will check the tnsnames.ora file to ensure that
london is a valid destination.