How does indexing work? What happens when books are updated or after I purchase books?
It works well - and you need not concern yourself with the technical details of what algorithm Faithlife used. You should simply trust that if no warning is shown that indexing is underway, Logos has kept your indexes up to date with new purchases and updates of the existing library. When there is an indication that the system is currently indexing, be aware that some data/resources may be missing -- if you suspect it is critical data, simply wait until the indexing completes.
It happens automatically. When you make new purchases, indexing automatically occurs.
Bob
One source of information is the Logos wiki, which is created by users.
Here you will find an article on "Installation and Indexing Questions".