Instant Client FAQ


Is Pro*C supported in Instant Client?

Yes, Pro*C is supported to run with Instant Client 10.2.0.x on Unix platforms. Pro*C is not supported with Instant Client on Windows currently.

   Modified: 09-APR-07    Ref #: ID-3661

Can ISVs bundle Instant Client?

Instant Client can be bundled by anyone that can bundle the regular Client, including Embedded License holders. ISVs can redistribute Instant Client along with their own packaged applications for free.

   Modified: 25-FEB-04    Ref #: ID-3666

Does Instant Client work with Oracle Names?

No, Instant Client does not work with Oracle Names. While Instant Client is backwards compatible with older databases, it does not support now deprecated features, including Oracle Names. Please see the Metalink Note.

   Modified: 08-JUL-04    Ref #: ID-5588

Is SQL*Plus supported by Instant Client?

Yes, SQL*Plus can be used in conjunction with Instant Client. Just download the SQL*Plus package for your platform.

   Modified: 13-FEB-04    Ref #: ID-3664

Can Instant Client be redistributed?

Yes. Instant Client can be redistributed by ISVs to their customers in their custom installations. Enterprises can redistribute Instant Client within their organizations. However, customers can only call Oracle Support for Instant Client if they have a standard support contract. Please refer to the Instant Client License, available here:

   Modified: 01-DEC-05    Ref #: ID-4379

What does Instant Client cost?

Instant Client is FREE for anyone to use in a development or production environment. However, customers can only call Oracle Support if they already have a standard support contract.

   Modified: 04-FEB-04    Ref #: ID-4384

What can Instant Client be used for?

Instant Client can be used to run your OCI, OCCI, Pro*C, JDBC, and ODBC applications without installing a full Oracle Client. In addition, Instant Client supports SQL*Plus. As of Instant Client 10.2, it is also possible to develop applications for OCI and OCCI using the Instant Client SDK download.

   Modified: 01-DEC-05    Ref #: ID-4386

How do I specify connection strings in Instant Client mode?

All Oracle net naming methods that do not require use of ORACLE_HOME or TNS_ADMIN (to locate configuration files such as tnsnames.ora or sqlnet.ora) work in the Instant Client mode. In particular, the connect string can be specified in the following formats:

A SQL Connect URL string of the form:

//host:[port][/service name]

such as:


As an Oracle Net keyword-value pair. For example:


Naming methods that require TNS_ADMIN to locate configuration files continue to work if the TNS_ADMIN environment variable is set.

If the TNS_ADMIN environment variable is not set, and TNSNAMES entries such as inst1, and so on, are used, then the ORACLE_HOME variable must be set, and the configuration files are expected to be in the $ORACLE_HOME/network/admin directory.

Please note that the ORACLE_HOME variable in this case is only used for locating Oracle Net configuration files, and no other component of Client Code Library (OCI, NLS, and so on) uses the value of ORACLE_HOME.

The bequeath adapter or the empty connect strings are not supported. However, an alternate way to use the empty connect string is to set the TWO_TASK environment variable on UNIX, or the LOCAL variable on Windows, to either a tnsnames.ora entry or an Oracle Net keyword-value pair. If TWO_TASK or LOCAL is set to a tnsnames.ora entry, then the tnsnames.ora file must be able to be loaded by TNS_ADMIN or ORACLE_HOME setting.

   Modified: 08-APR-04    Ref #: ID-4428

How does Instant Client interact with an ORACLE_HOME?

As long as the library loading path has the directory containing Instant Client files (e.g. the instantclient directory) ahead of library directory in ORACLE_HOME, the application will operate in the Instant Client mode, and the libraries in the ORACLE_HOME will not be used.

   Modified: 25-FEB-04    Ref #: ID-4430

What behavior changes can I expect for Oracle environment variables?

Environment variables ORA_NLS33, ORA_NLS32, and ORA_NLS are ignored in the Instant Client mode. The ORA_TZFILE environment variable should be set to the name of the large timezone file as opposed to its full path. All other environment variables (such as NLS_LANG) have no change in behavior.

   Modified: 25-FEB-04    Ref #: ID-4432

Why do I get an error with the message "message file not found"?

Some Oracle applications are currently certifying operation under Instant Client. Once certification is complete, the message will disappear.

   Modified: 04-MAR-04    Ref #: ID-4568

Why do I see an increased virtual memory footprint when running my applications in conjunction with Instant Client?

The Instant Client libraries occupy a virtual address space that is equal to the size of the files. However, only frequently used error messages from the libraries occupy physical memory. Under most cases, the physical memory load is a few kilobytes despite the larger reserved virtual address space.

   Modified: 04-MAR-04    Ref #: ID-4570

How can Instant Client on Windows use registry settings?

Special settings for Instant Client enabled applications can be set in the registry for all users or on a per-user basis.
1. Using a registry editor (regedit or regedt32), go to HKEY_LOCAL_MACHINE\SOFTWARE for a global setting (or HKEY_LOCAL_MACHINE\HKEY_CURRENT_USER\SOFTWARE for each specific user).
2. Add ORACLE group key.
3. Add a new string value within the ORACLE key for the different settings you are interested in (NLS_LANG, TNS_ADMIN, etc.). For keys that are directories, use a fully qualified path.

   Modified: 06-APR-04    Ref #: ID-4988

How does Instant Client interact with an existing ORACLE_HOME-based client installation?

If you already have Oracle Client installed on your machine, then we recommend:
1. Do NOT unzip or copy the Instant Client libraries to either of ORACLE_HOME/lib or ORACLE_HOME/bin directories, to avoid overwriting files and leaving the installation in an inconsistent state. In general, we recommend putting the Instant Client libraries into a separate clean directory.
2. Do NOT put both the Instant Client directory AND the Oracle Client directory in the Library Path, regardless of ordering. Please use either one or the other in the Library Path (LD_LIBRARY_PATH or PATH, depending on platform), but not both, based on the version you wish to use.

   Modified: 06-APR-04    Ref #: ID-4990

How do I ensure that my "tnsnames.ora" file is being used in Instant Client?

Always set the TNS_ADMIN environment variable or registry to the location of the tnsnames.ora file (full directory path only, do not include the file name). This practice will ensure that you are using the appropriate tnsnames.ora for your application when running with Instant Client.

   Modified: 08-APR-04    Ref #: ID-5028

What is the interoperability of Instant Client with various database versions?

The Instant Client interoperates with any database version that the full Oracle Client interoperates with. Please see the interoperability matrix:

Metalink Note 207303.1

   Modified: 17-MAY-04    Ref #: ID-5348

Can LDAP be used with Instant Client?

Yes, LDAP can be used with Instant Client, as of

   Modified: 01-DEC-05    Ref #: ID-8434

false ,,,,,,,,,,,,,,,,