As of now an index will speed up searches for an exact match string and a substring ending with a "*".
It does NOT currently speed up searches starting with a "*", which is what we need to be implemented.
Example: in our unified messaging application - when we receive an incoming call - we have to find a user whose telephone number ends with the digits signaled to us by the telephone network.
Let's say a user has a telephone number +49(777)12345678. The telephone network only signals its extension 678. We thus search for *678 to get a list of possible users and by applying some extra magic we are able to pick the right one.
The problem is: we need to do this fast, because taking the call depends on it.