Huge collections have huge indexes that may not fit into RAM. Is that problem entirely solved with sharding ?
If I have lots of small collections with small indexes, what are the options for storing them ? Since only very few of them would be bigger than 200mb they wouldn't be eligible for sharding. What MongoDB database architecture can hold a huge number of fairly small collections ? Since all the queries would be to a specific collection, would this be as fast as a targeted query in a sharding environment ? Faster ?