Character Set Support for Distributed Environments

Oracle Database supports environments in which clients, Oracle Database servers, and non-Oracle Database servers use different character sets. NCHAR support is provided for heterogeneous environments. You can set a variety of National Language Support (NLS) and Heterogeneous Services (HS) environment variables and initialization parameters to control data conversion between different character sets.

Character settings are defined by the following NLS and HS parameters:

Parameters	Environment	Defined For
`NLS_LANG` (environment variable)	Client/Server	Client
`NLS_LANGUAGE` `NLS_CHARACTERSET` `NLS_TERRITORY`	Client/Server Not Heterogeneous Distributed Heterogeneous Distributed	Oracle Database server
`HS_LANGUAGE`	Heterogeneous Distributed	Non-Oracle Database server Transparent gateway
`NLS_NCHAR` (environment variable) `HS_NLS_NCHAR`	Heterogeneous Distributed	Oracle Database server Transparent gateway

Client/Server Environment

In a client/server environment, set the client character set to be the same as or a subset of the Oracle Database server character set, as illustrated in Figure 31-6.

Figure 31-6 NLS Parameter Settings in a Client/Server Environment

Description of "Figure 31-6 NLS Parameter Settings in a Client/Server Environment"

Homogeneous Distributed Environment

In a non-heterogeneous environment, the client and server character sets should be either the same as or subsets of the main server character set, as illustrated in Figure 31-7:

Figure 31-7 NLS Parameter Settings in a Homogeneous Environment

Description of "Figure 31-7 NLS Parameter Settings in a Homogeneous Environment"

Heterogeneous Distributed Environment

In a heterogeneous environment, the globalization support parameter settings of the client, the transparent gateway, and the non-Oracle Database data source should be either the same or a subset of the database server character set as illustrated in Figure 31-8. Transparent gateways have full globalization support.

Figure 31-8 NLS Parameter Settings in a Heterogeneous Environment

Description of "Figure 31-8 NLS Parameter Settings in a Heterogeneous Environment"

In a heterogeneous environment, only transparent gateways built with HS technology support complete NCHAR capabilities. Whether a specific transparent gateway supports NCHAR depends on the non-Oracle Database data source it is targeting. For information on how a particular transparent gateway handles NCHAR support, consult the system-specific transparent gateway documentation.