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db.collection.reIndex()drops all indexes on a collection and recreates them. This operation may be expensive for collections that have a large amount of data and/or a large number of indexes.
Changed in version 2.6: Reindexing operations will error if the index entry for an indexed field exceeds the
Maximum Index Key Length. Reindexing operations occur as part of
repairDatabase commands as well as the
Because these operations drop all the indexes from a collection and then recreate them sequentially, the error from the
Maximum Index Key Length prevents these operations from rebuilding any remaining indexes for the collection and, in the case of the
repairDatabase command, from continuing with the remainder of the process.