Loading DataTables and FormGroups in the iSeriesC environment

How you load DataTables and FormGroups can affect the performance of your EGL programs in the iSeriesC environment.
You can improve the performance for loading DataTables and FormGroups by storing the binary DataTables and FormGroups in the following Integrated File System (IFS) stream files rather than in database files:

Use the CPYTOSTMF (Copy to Stream File) command to copy the binary DataTable and FormGroup from the database file to the stream file. The stream file must reside in the /QVGN subdirectory in the root file system; otherwise, EGL Server for IBM® i cannot find the DataTable and FormGroup as stream files. The /QVGN subdirectory is automatically created at installation.

Best practice is to copy EGL DataTables and FormGroups to the IFS stream files only after the EGL application is placed into production. Programs must be in production because the subdirectories in the IFS stream files, in this case /QVGN (which contains the DataTables and FormGroups), are scoped to all iSeries® jobs on the system. Testers of programs that use DataTables and FormGroups stored in the IFS stream files should access the stream file instance of the DataTables and FormGroups rather than the developer copy of the DataTables and FormGroups in database files *LIBL/QVGNTAB and *LIBL/QVGNMAPG.

For more information, see the i5/OS™ Information Center. To list IFS system commands, enter GO DATA on an IBM i command line.

Note: All binary image DataTable and FormGroup files that you want to copy to stream files must reside in the same /QVGN root subdirectory. Ensure that all DataTables and FormGroups have unique names. DataTables and FormGroups that occur within an EGL package have unique names, but DataTable and FormGroup names from various EGL packages or projects might collide.

If you do not copy DataTables and FormGroups into stream files in the /QVGN root subdirectory, loading DataTables and FormGroups can be slower. The binary DataTable and FormGroup files are stored in the native library system as database files in QVGNTAB and QVGNMAPG. This occurs automatically when the EGL build scripts prepare the output of generation.

You can use any combination of DataTables and FormGroups in stream files and database files. To load DataTables and FormGroups, EGL Server first searches the /QVGN subdirectory for the DataTable or FormGroup. If the DataTable or FormGroup does not exist as a stream file, EGL Server loads the DataTable and FormGroup from the *LIBL/QVGNTAB and *LIB/QVGNMAPG database files.


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