Informix Guide to GLS Functionality Database Server Features

The database server can perform read and write operations to the following operating-system files:

• Diagnostic files

Diagnostic files include the following files:

• af.xxx
• shmem.xxx
• gcore.xxx
• core

The database server generates diagnostic files when you set one or more of the following configuration parameters:

• DUMPDIR
• DUMPSHMEM
• DUMPCNT
• DUMPCORE
• DUMPGCORE

• Message-log file

The database server generates a user-specified message-log file when you set the MSGPATH configuration parameter.

These operating-system files reside on the server computer, where the database server resides. When the database server reads from or writes to these files, it must use a code set that the server computer supports. The database server obtains this code set from the server locale.

Set the server locale with the SERVER_LOCALE environment variable. If you do not set SERVER_LOCALE, the database server uses the default locale, U.S. English, as the server locale. For more information, see SERVER_LOCALE.

For Enterprise Decision Server, all coservers must have identical GLS operating-system environments.

To perform code-set conversion and handle non-ASCII characters that are associated with read and write operations on operating-system files, the database server determines the server code set (the code set that the server locale supports). For information about the use of non-ASCII characters, see Non-ASCII Characters in Identifiers.

This section summarizes the code-set conversion that the database server performs. For more general information about code-set conversion, see Performing Code-Set Conversion.

An Informix database server automatically performs code-set conversion between the code sets of the server-processing locale and the server locale when the following conditions are true:

• The CLIENT_LOCALE, DB_LOCALE, and SERVER_LOCALE environment variables are set such that the code sets of the server-processing locale and the server locale are different.
• A valid code-set conversion exists between the code sets of the server-processing locale and server locale.

For a list of files for which Informix database servers perform code-set conversion, see GLS Support by Informix Database Servers. For information on GLS code-set conversion files, see Code-Set-Conversion Files.

Once the database server creates the operating-system file, it has generated a filename and written file contents in the code set of the server locale (the server code set). Any Informix product or client application that needs to access this file must have a server-processing locale that supports this same server code set. You must ensure that the appropriate locale environment variables are set so that the server-processing locale supports a code set with these non-ASCII characters. For more information about the server-processing locale, see Determining the Server-Processing Locale.

The database server checks the validity of a filename with respect to the server-processing locale before it references a filename.

Enterprise Decision Server rejects any filename that is not ASCII alphanumeric 7-bit.

When the database server transfers data to and from its operating-system files, it handles any differences in the code sets of the server-processing locale and the server locale as follows:

• If these two code sets are the same, the database server can read from or write to its operating-system files in the code set of the server locale.
• If these two code sets are different and an Informix code-set conversion exists between them, the database server automatically performs code-set conversion when it reads from or writes to its operating-system files.

For code-set conversion to resolve the difference in code sets, the server locale must support the actual code set that the database server used to create the file. For more information, see Making Sure That Your Product Supports the Same Code Set.

• If these two code sets are different, but no Informix code-set conversion exists, the database server cannot perform code-set conversion.

If the database server reads from or writes to an operating-system file for which no code-set conversion exists, it uses the code set of the server-processing locale to perform the read or write operation.