Is scalability really an important argument for everyone?
I mean, a doctor only needs access to his direct patients in, say, half a year. He never looks at any other patients in his system.
How many patients are that, 5000, 10000? Maybe even 20000. The largest scale is hospital scale, but even in hospitals are situations with distributed systems desirable or even fact.
For National Healthservices, you don't need central systems with millions of patients, but you need a good message-system, and an index-server, which is not a medical information system.
For disease-control, epidemiological warming systems, or for medical research purpose, you don't need to have access to all patients on a single cluster, it is enough to make smart use of semantic webs and/or eventually, distributed queries.
Even in hospitals, in the Netherlands, hospitals are markets for specialist, which work on their own account or in small businessgroups for hospitals and also inside the hospital-buildings.
Often they have their own information systems, and often with bad messaging. That needs improvement. The hospital itself also offers services, and has information systems for that. For example, financial accounting, medication, and beds and nurses.
Only academic hospitals in the Netherlands have specialist in service for the hospital, and they have central information systems, and there are advantages to that, but there are more ways.
When you have 10 million patients on one machine-cluster, is the same as having 10000 patients on 1000 machines. Most of these patients live on more systems, at the GP, dentist, local hospital, insurance, etc. So, those 10 million patients live on perhaps 5000 machines, machines with systems with different requirements.
This is the situation in most countries, and this will not change in most countries. There is a lot of opposition of several groups against central machines, not only privacy concerns, but also how will the software-companies make money if the government hijacks their market? In the liberal market situation most governments will not chose for central systems. At least not in coming decades. Unless North Korea wins the war, of course.
Health related arguments are thus not the only arguments which decide how the Health-information landscape will look.
Those 1000 machines are cheap, not depending hard on the internet, software can be available on sharp markets, competition in features and price, the government can guard quality rules.
Most of us are not building a single National Healthservices cluster with all patients centralized stored. Realize that and life becomes more simplier, you can concentrate on other, more important things.
If you cannot let go the dream of being the one who delivers the National Healthservices cluster, make you storage-layer transparant, so with it can be exchanged with not much effort. You should do that anyway, at every system-designer school you learn that.
Keep in mind that the other software layers in your system do not need to know on which kind of database they run.
This all is only about scalability for databases/systems. We do need scalability on other subjects, like in the discussion between Tom and Tim on identification on archetyping, and identification of patients, etc.
So even when you are designing a small system, you need to remember that it must be possible to safely share information with thousands of systems. That is not scalability in database, but in logical design.
Have a good day,
Bert Verhees
