How MongoDB manage data after inserting?

Question

After data is inserted into the db, I know that MongoDB stores the data in files, however, I'm confused about memory.

Supposing when I will insert 50 million records into the db - will this data be loaded in memory? If not, how does MongoDB behave to keep its performance?

Answer 1

In that case documents are loaded into memory on request by blocks, that mean our collection is split-ed into chunks, and most frequent used chunks resides in memory. To gain performance mongo uses indexes and there is a special query called coved query which means that all data needed is stored in index, which is smaller than collection.