Correctness and conformity of all components of some data structure are referred to as integrity of this structure. If the program of data processing does not contain serious errors, the reason for integrity break can be related only with computer hardware failures or with external reasons, such as switch off of power supply while making data changes. Losing of GDB or shared library integrity can result in complete or partial losing of a possibility to use the corresponding data.
Integrity check is performed by the command GDB+Check Integrity. The system starts the integrity check wizard. The first page of this wizard window is shown at figure 6-6.
Figure 6-6. Integrity check wizard. Step 1
First of all the user should select the integrity of which particular structure should be checked: shared style library or some GDB. In case of GDB check it is also necessary to select a particular GDB for checking. To do this the user has to use the button Browse in the pane Check. As it was noted above, it is impossible to select the current GDB for checking.
If the user worked in the mode of working with change file for GDB or shared library being checked, he should decide integrity of which data should be checked: only the data which is contained in the nine main files or also the data in the change file (to perform this it is required to check the box Use change file). Of course, if there are no errors all the data should keep its integrity, however, in practice it is possible that the main files will keep data integrity and the integrity of the change file data is broken.
After that it should be determined if it is necessary to save the report about the file check (in any case this report will appear on the screen). If the user checks the box Make report, he should specify the name of the report file using the button Browse (the one that is in the Report file pane). If the existing report file is selected the user also decides whether he should replace the previous report contents by new ones (if radio button Overwrite is checked) or accumulate several reports (for example, when checking several GDB) in one file (check button Append). For report files on integrity check the system uses CHK extension.
After pushing the button Next a second wizard page shown at figure 6-7 is opened
Figure 6-7. Integrity check wizard. Step 2
The purpose of this page is to select which particular components of the inner representation of selected GDB or shared library should undergo checking. The user does not need to have a good knowledge of inner GDB structure, though it will be useful to have the general understanding.
All GDB data, spatial as well as attributive, are stored as tables of object-oriented database which is the basis of GDB representation in ObjectLand. That is why the word “Tables” which is repeated three times in the left part of the page denotes not only data contained in GDB tables, but other data types as well. They are all grouped in three databases.
Definition database contains data about GDB structure (GDB components and their properties, style library, etc.);
Table database contains records of all GDB tables;
Map database contains description of all GDB features.
Every area also has index data which is used for speeding up the search.
The necessity of checking such data types as map feature links with table records and also integrity of map layer structure is indicated separately.
If the issue of reducing time for checking is not critical it may be recommended to leave all the boxes checked on this page which results in a more complete GDB check.
Then, after pushing the button Next again, the third wizard page is opened. After pushing the button Check messages about checking different components of inner representation are displayed on the pane of this window. At figure 6-8 a wizard window of integrity check in the process of checking is shown.
Figure 6-8. Wizard check of GDB integrity. Executing check
Messages about the check will be useful for advanced users or ObjectLand developers. For an ordinary user it is enough to know that if there are no errors, the check is completed and the following message is displayed: “Check completed. Errors: 0”.
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