This mode permits gathering all the changes made to GDB in a special change file and not to include them directly into the main GDB files.
If the user doesn't have sufficient experience in working with the change file, there is a danger of losing data. That is why it is prohibited to use this mode right after ObjectLand installation. For getting permission to work with the change file it is required to use the menu command GDB+Settings (see chapter 8 “System parameters setting”).
If the user opened GDB in the mode of using change file, the results of every operation changing database or its data structure will be recorded not into GDB files, but in the change file. When closing GDB the system usually warns the user about the presence of changes not entered into GDB files, however, it is possible to switch off the display of this message.
Change file has the same name as the corresponding GDB and has CHG extension. Usually it is located in GDB folder but it is possible to specify another location.
After closing GDB its current state is actually stored both in GDB files and in the change file. When a user opens GDB in the mode using the change file again, the system reads data from both sources and shows GDB in the changed form. The user can continue to make changes, and they will be accumulated in the change file as long as necessary.
If the same or different user opens the present GDB for reading without the change file he will find that the changes made are not displayed since these changes are not in GDB files.
When the user takes the final decision about including all the changes into the core of GDB he should perform GDB consolidation operation. The essence of this operation is that all recorded changes are moved from the change file to GDB files. After consolidation the change file is removed.
Consolidation operation is performed only with the closed GDB.
On no account non-consolidated GDB should be opened in the writing mode without the change file. It may lead to either data corruption or losing of all earlier GDB changes stored in the change file.
After GDB consolidation the user can continue working with the change file or use the open mode without the file of changes further.
If the user decides to reject all the changes made after the last GDB consolidation, it is enough to remove the change file by means of the operating system. It can be done only when the present GDB is closed by all the users.
If shared access mode is used then either all the users should use the change file or none of them can use it. The choice in this case is made by the user who opens the GDB first.
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