T 4.30 Loss of database integrity/consistency

The loss of the integrity or consistency of a database means that the data in the database is still present, but is in an incorrect or corrupt state. As a result, the data cannot be accessed correctly or cannot be processed correctly any more. A database inconsistency can be caused by a wide variety of causes, for example inadvertent data manipulations (accidental changes to data), incorrect transaction synchronisation control, or even deliberate attacks.

A database inconsistency can result in the following consequences, among others:

• It may become impossible to perform certain tasks that depend on correctness of the data in the database, or it may be impossible to finish these tasks.
• The information contained in the data may become corrupt.
• It could involve a great deal of effort to restore the integrity and consistency of the data in the database.

Depending on the reason for the database integrity/consistency violation, it may be difficult or impossible to determine which data was modified (see also T 2.22 Lack of or insufficient evaluation of auditing data). This can result in additional financial losses or pose additional security risks.

Examples:

• Due to a lack of time and space, a file for a database was created in the /tmp file system on a Unix server. This file system was automatically deleted overnight, and the entire database became unusable after the deletion.
  An electronic archive uses a database in which all archived documents are indexed. If the indexes or references to individual documents are lost, it may be impossible under certain circumstances to find them again without a considerable amount of effort. Such a loss of the database integrity can subsequently result in significant financial losses or legal damages.