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An open source clone of Amazon’s Dynamo database created by LinkedIn, Voldemort has a classic three-operation key/value interface, but with a sophisticated backend architecture to handle running on large distributed clusters. It uses consistent hashing to allow fast lookups of the storage locations for particular keys, and it has versioning control to handle inconsistent values. A read operation may actually return multiple values for a given key if they were written by different clients at nearly the same time. This then puts the burden on the application to take some sensible recovery actions when it gets multiple values, based on its knowledge of the meaning of the data being written. The example that Amazon uses is a shopping cart, where the set of items could be unioned together, losing any deliberate deletions but retaining any added items, which obviously makes sense—from a revenue perspective, at least!

Source of Information : Big data Glossary