Oracle 10g introduces a lighter weight database client called Oracle Instant Client. Oracle Instant client allows you to get away from the standard Oracle Client installation for running applications from desktops or Servers. All applications that need OCI, Pro*C, ODBC, and JDBC will work without any issues and this client takes significantly less disk space than a full 10g client.

Instant client also supports SQL*Plus, without having to recompile ro relink the code. Enterprise support teams can now take advantage of this simpler installation and the smaller footprint to automate setup and configuration of Oracle Instant Client.

The installation process involves
1. Downloading the package from OTN
2. Unzip the package into a directory of your choice
3. Set the PATH variable ( LD_LIBRARY_PATH in Unix )
4. Set TNS_ADMIN variable if you want Instant client to find your TNS Names.

The above variables can also be set under HKEY_LOCAL_MACHINE\SOFTWARE\ORACLE.

Voila, you have Oracle client ready to go.

Oracle Instant Client Packages

The following basic packages are of the most use to many of the users in the network.
Basic Package : Comes with all files required to run OCI, JDBC-OCI applications.

Basic-Lite Package : Smaller version of the Basic, with only English error messages and Unicode, ASCII, and Western European character set support (10.2 only)

SQL*Plus : Additional libraries and executable for running SQL*Plus with Instant Client

Other supplements are available for XA, JDBC, ODBC etc., and serve special purposes that the above packages would not be able to handle.