A generation data group (GDG) is a chronological collection of related files. GDGs simplify the processing of multiple versions of related data.
Each file within a GDG is called a generation data set (GDS) or generation. (In this information, generation data sets are referred to as generation files. The term file on the workstation is equivalent to the term data set on the host.)
Within a GDG, the generations can have like or unlike attributes including ORGANIZATION, record format, and record length. If all generations in a group have consistent attributes and sequential organization, you can retrieve the generations together as a single file.
The generations within a GDG have sequentially ordered relative and absolute names that represent their age.
For more information about forming absolute and relative names, see the related tasks.
Generation order is typically but not necessarily the same as the order in which files were added to a group. Depending on how you add generation files using absolute and relative names, you might insert a generation into an unexpected position in a group. For details, see the related reference about insertion and wrapping of generation files.
GDGs are supported in all of the COBOL for AIX file systems.
For information about creating and initializing generation data groups, see the appropriate related task.
To delete, rebuild, clean up, modify, or list generation groups, or add or delete generations within a group, use the gdgmgr utility. To see a summary of gdgmgr functions, issue the following command: gdgmgr -h. For further details about the gdgmgr utility, see its man page.
related tasks
Creating generation data groups
Using generation data groups