Database Reference
In-Depth Information
Chapter 11
Tuning Oracle Net
In an
n
-tier architecture solution, each tier connects to the other via a network component. An Oracle database that
normally resides on the database tier provides connectivity via a network layer.
Oracle application systems use an SQL Net interface between the Oracle application software and the underlying
network protocol layer. By using these interface layers, users accessing the database are able to access, modify, share,
and store data.
There are two phases when the user accesses the database to retrieve or store the data: the connect phase and
the query phase. The connect phase is where the application server makes a connection on behalf of the user to the
physical database. The query phase involves retrieving or storing the data into the physical database.
The user makes a connection to the database for one of several operations
•
To insert rows into the database; data is sent from the client application to the database server
via a network layer
•
To select data sets from the database, which involves sending data from the database and
servers to the application servers, again using the network layer
•
A mixture of the preceding two operations where data is selected, modified, and loaded back
into the database
Both of these phases play an important role in the overall response time of the user operation. Whereas the query
phase can be tuned using database-related parameters and layout structures, the connect phase depends on several
factors. Some of these factors include the type of network interface, network bandwidth, availability of the listener, the
availability of the instance, number of sessions permitted on the instance, and so forth.
Making the Connection
In a typical implementation, a database request starts when a client (SQL plus client or an application server) makes
a connection to the database application. This request for connection, at a very high level, is received by the listener
on the database server; and if the requested database service through the connect descriptor is registered with the
listener, the listener parses the connection request to the database instance on the server.
The connection initiation client can be one or more of these types: SQL Plus or application server that uses a Java
Database Connectivity (JDBC) thick client or thin client. Once the connection is initiated, as illustrated in Figure
11-1
,
it has to traverse through the stages and layers of network stack before making a physical connection to the database.
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