Oracle SQL NET transparent network
Oracle Tips by Burleson Consulting
The Data Warehouse Development Life Cycle
The Internals Of Oracle's SQL*Net
In version 2.0, Oracle has added several important enhancements
to SQL*Net. Aside from the badly needed bug fixes, SQL*Net now
allows multiple community access. A community is a group of
computers that shares a common protocol (such as TCP/IP to LU6.2).
In addition, the Oracle database engine now defines a multithreaded
server (MTS) for servicing incoming data requests. In the MTS, all
communications to the database is handled through a single
dispatcher. In SQL*Net version 1.0, a separate process is spawned
for each connection. These connections are easily viewed by using
the Unix ps command.
When upgrading from SQL*Net 1.0 to SQL*Net 2.0, you should be aware
of subtle differences between how the two versions handle
communications (see Figure 9.12). SQL*Net version 1.0 uses an orasrv
component on the destination database to listen for incoming
requests, while SQL*Net 2.0 uses a process called tnslsnr (TNS
listener). In addition, SQL*Net 1.0 cannot use the multithreaded
Figure 9.12 The two versions of SQL*Net.
When a connection is made to SQL*Net, it passes the request to its
underlying layer--the transparent network substrate (TNS)--where the
request is transmitted to the appropriate server. At the server,
SQL*Net receives the request from TNS and passes the SQL to the
database. Transparent network substrate is a fancy phrase meaning a
single, common interface to all protocols that allows you to connect
to databases in physically separate networks. At the lowest level,
TNS communicates to other databases with message-level send and
This is an excerpt from "High Performance
Data Warehousing", copyright 1997.
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