In MongoDB 2.5.5, the server got a "createIndexes" command that replaces the old method of inserting an index spec into the system.indexes collection (SERVER-1627). Beginning in 2.7.5, the server can build multiple indexes efficiently: it faults in each document just once to gather information for multiple indexes.

In DRIVERS-132, drivers with a "create_index" helper were updated to use the createIndexes command instead of inserting into system.indexes, when talking to a newer server. However, drivers were not required to allow users to pass multiple index specs at a time to createIndexes. We should add this ability.

This DRIVERS ticket needs a spec.