Methods and systems for automatically resharding a sharded collection of data

A method is provided for resharding a sharded database sharded according to a first shard key. The method includes: receiving, by a processor an instruction to reshard the sharded database; receiving, at the processor, a new shard key to be used in a resharding process to reshard the sharded database; determining, by the processor, whether a duration of unavailability of the sharded database during the resharding process is less than a predetermined amount of time; and automatically performing, by the processor, the resharding process according to the new shard key to produce a resharded database, if the duration of unavailability is less than the predetermined amount of time. The method may be performed without users noticing a significant interruption to read/write operations from/to the database.