On Saturday 20 October 2001 08:53, you wrote:
> Andre,
>
> The only reason to have data for one query in different databases is if
> the databases are on different machines. If you're running on PC-type
> hardware, you might have to do that some times for performance reasons.
> But if at that point, you should ask yourself if you shouldn't invest in
> some faster hardware ;-).
There are many more good reasons to do so. Example from my own domain,
medicine:
1.) one database hold demographic information. This information is needed by
administration, nursing, and medical staff as well as by external service
providers such as pathology.
2.) another database holds medical information. The information here is
highly sensitive. The database admin should be a medical doctor,and it must
be unaccessible to clerical staff. SQL permissions are only a *very* weak
protection, not good enough for this purpose. For many good reasons, foremost
security, this information will not reside in the same database (sometimes
not even on the same machine) as the administrative data or the demographic
data.
3.) For obvious reasons, it would be bad to replicate the demographic data in
order to provide this data to administration, medical staff etc for their own
purposes.
Thus, we have multiple databases on multiple servers all depending on each
other. Some servers are read-only, others need the backend to log every
single query for audit trailing. The latter alone would blow the storage
needs out of proportion if applied to the whole set of databases. At present,
it is up to our client software to sort this out "manually". A minor
headache.
Horst
