MongoDB: Trade-offs of dropping a collection vs. removing all of its documents

Question

What are the trade-offs of dropping a MongoDB collection vs. removing all of its documents (assuming the collection will be re-created immediately)?

Answer 1

A benefit of simply dropping a collection is that it is much faster than removing all of a collection's documents. If your collection will be "re-created immediately" anyway (assuming that includes index re-creation), then this is probably the most-attractive option.

The authors of the book MongoDB: The Definitive Guide (Kristina Chodorow and Michael Dirolf) ran an experiment where they provided a Python script which timed a drop vs. a remove of 1000000 records. The results came in at 0.01 seconds for the drop and 46.08 seconds for the remove. Now while the exact times may differ based-on hardware and other factors, it nonetheless illustrates the point that the drop is significantly faster.

reference: Chodorow K., Dirolf M. (2010). “MongoDB: The Definitive Guide.” O'Reilly Media, Inc. Sebastapol, CA., pp.25