Environment Considerations for Informix

Network Considerations

All Informix products possess integrated remote client/server communications. For more information on network and local connections, see your Informix documentation. Alternatively, you can use the Uniface Router and Server for transparent network connectivity.

NLS Support

NLS functionality in Informix can be activated by setting specific environment variables. The NLS data types Nchar and Nvarchar can be used in place of Char and Varchar to store national characters.

The specifications for the NLS data types Nchar and Nvarchar are similar to their non-NLS counterparts Char and Varchar with the following exceptions:

  • NLS data types can only be created, accessed, and manipulated in an NLS environment, and are therefore not backward-compatible with previous Informix versions.
  • NLS data types are relatively expensive in terms of performance.
  • Evaluation of regular expressions, sorting, and index building are done according to local values instead of ASCII values for NLS data types.

When NLS functionality is enabled, Char (Varchar) data columns are treated as Nchar (Nvarchar) data columns, except that sorting and other operations on the foreign character data are done according to ASCII conventions. This behavior can be bypassed by setting specific NLS environment variables.

Currently, there are no matching Uniface packing codes for the Informix NLS data types Nchar and Nvarchar. The connector, if requested, substitutes all Char and Varchar to Nchar and Nvarchar. All Uniface packing codes currently mapped to Char and Varchar are mapped to Nchar and Nvarchar at table creation time.

If the nls connector option is set, and Informix NLS functionality has been enabled, tables are created with Nchar and Nvarchar fields instead of Char and Varchar fields. If Informix NLS functionality is not enabled, the Informix database server generates an error and the table is not created.

No special consideration is necessary for manipulating the NLS data types since they can support only single-byte, 8-bit character code sets. Uniface is capable of supporting European characters through the DEC ISO Latin-1 character set.

It is not possible to create tables with both Char (Varchar) and Nchar (Nvarchar) fields via the connector. However, this can be accomplished by generate a create table script using the Create Table facility and modifying the data types for Char (Varchar) and Nchar (Nvarchar) manually.

For more information on NLS functionality, see your Informix documentation.