Repairs of a damaged database

Various action can lead to a database damage. E.g. there's a small loss of (unused) drive memory whenever a server is incorrectly terminated (such as a computer reset during its runtime).

602SQL is therefore equipped with tools that can search for and repair certain error types in the database structure. Database repairs can be executed either from the control panel (action System / Tools / Database consistency) or directly from a program by calling the (cd_)Database_integrity function.

The Database consistency action opens a dialog window, where you may specify the error types you're interested in by checking appropriate checkboxes. If you want to repair the errors as well, check the Repair errors box. Press the Start check button then. After a while the count of found or repaired errors.

When repairing errors:

if the Non-existing disk blocks box is checked, these objects return into the free disk memory control.
if the Cross-linked disk space box is checked, then each time that two database objects share the same part of disk memory, each of those two receives its own copy. Keep in mind that only one of these objects will have in this disk memory the correct data.
if the Damaged tables box is checked, then those tables are deleted that can't be any longer worked with due to a damaged definition in the system table. This action doesn't effect tables only containing damaged data.
if the Lost disk space box is checked, then the table and index references pointing "into nowhere" are deleted. Damaged tables export and work with undamaged parts of information should be unblocked for this action.
Outdated index - all indices are searched (including indices in the system tables) and if they're damaged, they'll get rebuilt.
Invalid cache of free records - this working cache get rebuilt according to the valid states of tables if necessary.

Error searching and repairing can take a long time in a complicated database.

For the first four error types repairs the server has to be locked - these actions won't get executed if some other entity (a user or a separate thread) is already connected. The remaining error types can be repaired at any time.

Rebuilding Indexes

Damaged Database Restoration Methods

Restoring a Database from Backup