http://en.wikipedia.org/wiki/Extensible_Storage_Engine
Amazing how powerful a database there is that is built right into Windows. Obviously it scales and is dependable because Microsoft’s most important and more deployed products rely entirely upon it – Exchange and Active Directory. Wonder why more of the stuff out of MSFT that needs a backend store doesn’t use it. Say like MIIS, MOM, etc…
ESE makes sense in embedded storage scenarios. IE, scenarios where you don’t have an interest in external apps querying your data set with anything but your own API.
For something like MOM event log DBs, it makes little sense. The reason is simple: they *absolutely* want people to have full SQL syntax against the aggredated data. That’s one the features.
While you can expose ESE data to external apps (eg: AD does this, obviously) it is hard. It means you write a QP that is sufficently complex & interesting for you data. This is an undertaking.
I can’t speak to MIIS as I don’t have as much of a feel for how they use the db. But it certainly might make sense there.