Do you need every record you add/update to the database to be there when you try to read it later or are you ok with a best effort to save that works to some 9x.xxxxx degree but occasionally drops some things?
If it needs to be there, use a a fully transactional database.
It could mean that, or it could mean your user database or where you store your blog comments or your customer's todo lists. Basically anything where you want to make sure all the data is still there the next time you go looking for it.
