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Top1. Introduction
Electronic Health Records (EHRs) have high requirements to storage and reusability of information. The stored information has to be available for health care professionals at any given time, and furthermore, the health care professionals also need to be allowed to store new information gathered in a patient-near setting. (Koch, 2006; Digital Health, 2008) To meet the requirements for storage and reusability EHRs are based on large databases. These databases are often created, maintained and used through a DBMS. When using DBMS to manage databases an important aspect involves transactions which are any logical operation on data and per definition database transactions must be atomic, consistent, isolated, and durable in order for the transaction to be reliable and coherent.
The ACID properties of a database are delivered by a DBMS to make database recovery easier and make it possible in a multi user environment to give concurrent transactions a consistent chronological view of the data in the database. The ACID properties are consequently important for users that need a consistent view of the data in a database. However, the implementation of ACID properties may influence performance and thereby slow down the availability of a system in order to guarantee that all users have a consistent view of data even in case of failures. In several situations, the availability and the response time will be unacceptable if the ACID properties of a DBMS are used without reflection. Especially, in the case of distributed and/or mobile databases where a failure in connections of a system should not prevent the system to operate in a meaningful way in so-called disconnected mode.
Information systems that operate in different locations can be integrated by using more or less common data and/or by exchanging information between the systems involved. In both situations, the union of the databases of the different systems may be implemented as a database with so called relaxed ACID properties where temporary inconsistencies may occur in a controlled manner. However, when implementing relaxed ACID properties it is important that from a user’s point of view it must still seem as if traditional ACID properties were implemented, which therefore will keep EHRS trustworthy for decision making.
In the following part of the introduction, we will give an overview of how relaxed ACID properties may be implemented and used to integrate EHRs from different types of health institutions.