1 Introduction

In many industries significant effort is needed to keep organisation specific databases in sync with each other. In the financial sector the effort of keeping different databases synchronised, reconciling them to ensure they actually are synchronised and resolving the ‘breaks’ that occur when they are not represents a significant fraction of the total work a bank actually does! Why not just use a shared relational database? This would certainly solve a lot of problems using only existing technology, but it would also raise more questions than answers:

• Who would run this database? Where would we find a sufficient supply of angels to own it?
• In which countries would it be hosted? What would stop that country abusing the mountain of sensitive information it would have?
• What if it were hacked?
• Can you actually scale a relational database to fit the entire financial system?
• What happens if The Financial System™ needs to go down for mainte- nance? • What kind of nightmarish IT bureaucracy would guard changes to the database schemas?
• How would you manage access control