If someone try to develop application like google doc or sheet what kind of database should they use ? As such document object will require periodic update saving in every time fraction. Many database keeps old data(row) version to support MVCC and eliminates them later using VACUUM(Postgresql) and Compaction features(HBase). But as such document object tends to be big, database can get bloated sooner.

SO my question is:

1. What is the best database to use for such use cases
2. Or, if we want to use database like Postgresql/Hbase how could we structure data especially XL sheet.

I would highly appreciate if some architectural hints could be provided.

Thanks in advance.