Many people known context of file they are searching for. For example: If I search financial file, I knew it it related to life activity or to business activity. If I search for files related to choose of trip, I will known it is related to life, etc.
So: split baloo indexes around activities, or allow user to do so, for example by assigning directory to activity, so each file inside will be related to this activity.
Thanks to that, we could speed up searching, indexing (because we have smaller search tree to rebuilt), reduce memory consumption (because we must keep only search tree related to current activity, if indexes will be smaller thanks to realize this idea, we can kept on disk and kept only one in memory), etc.
There are many pluses.
What do you think?