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An open source clone of Amazon's Dynamo.
Java Python C++ Ruby Shell Scala Other
Pull request Compare This branch is 19 commits ahead, 1781 commits behind voldemort:master.
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.settings Implement Issue 155: Upgrade to protobuf 2.2.0.
bin Added option to set rebalancing steal information using the admin tool
clients a) Fixed async listing in admin tool
config Added back view prototype store to the single node cluster metadata
contrib Some more fixes - This version works! :)
docs Updating omnigraffle for logical architecture
example/java/voldemort/examples Server side transforms changes to client interface
lib Added support for snappy + Got rid of old code from LZF and instead r…
src Got rid of dependency on CheckSum
test Run warmup as a flag
.classpath Added support for snappy + Got rid of old code from LZF and instead r…
.gitignore Removed AdminClientOld2.
.project Initial import
CONTRIBUTORS Added Voldemort Web Manager
LICENSE Add license header to source files.
NOTES Add support for protocol buffers based network format. Add new client…
NOTICE Add Avro, Jackson and ParaNamer to NOTICE. fix README markup and few typo errors Bumping up the version to 0.90!
build.xml Java doc changes
release_notes.txt Bumping up version to 0.90.RC5 Initial import
web.xml Initial import

Voldemort is a distributed key-value storage system

  • Data is automatically replicated over multiple servers.
  • Data is automatically partitioned so each server contains only a subset of the total data
  • Server failure is handled transparently
  • Pluggable serialization is supported to allow rich keys and values including lists and tuples with named fields, as well as to integrate with common serialization frameworks like Protocol Buffers, Thrift, and Java Serialization
  • Data items are versioned to maximize data integrity in failure scenarios without compromising availability of the system
  • Each node is independent of other nodes with no central point of failure or coordination
  • Good single node performance: you can expect 10-20k operations per second depending on the machines, the network, the disk system, and the data replication factor
  • Support for pluggable data placement strategies to support things like distribution across data centers that are geographical far apart.

It is used at LinkedIn for certain high-scalability storage problems where simple functional partitioning is not sufficient. It is still a new system which has rough edges, bad error messages, and probably plenty of uncaught bugs. Let us know if you find one of these, so we can fix it.

Comparison to relational databases

Voldemort is not a relational database, it does not attempt to satisfy arbitrary relations while satisfying ACID properties. Nor is it an object database that attempts to transparently map object reference graphs. Nor does it introduce a new abstraction such as document-orientation. It is basically just a big, distributed, persistent, fault-tolerant hash table. For applications that can use an O/R mapper like ActiveRecord or Hibernate this will provide horizontal scalability and much higher availability but at great loss of convenience. For large applications under internet-type scalability pressure, a system may likely consist of a number of functionally partitioned services or apis, which may manage storage resources across multiple data centers using storage systems which may themselves be horizontally partitioned. For applications in this space, arbitrary in-database joins are already impossible since all the data is not available in any single database. A typical pattern is to introduce a caching layer which will require hashtable semantics anyway. For these applications Voldemort offers a number of advantages:

  • Voldemort combines in memory caching with the storage system so that a separate caching tier is not required (instead the storage system itself is just fast).
  • Unlike MySQL replication, both reads and writes scale horizontally
  • Data partioning is transparent, and allows for cluster expansion without rebalancing all data
  • Data replication and placement is decided by a simple API to be able to accommodate a wide range of application specific strategies
  • The storage layer is completely mockable so development and unit testing can be done against a throw-away in-memory storage system without needing a real cluster (or even a real storage system) for simple testing


The source code is available under the Apache 2.0 license. We are actively looking for contributors so if you have ideas, code, bug reports, or fixes you would like to contribute please do so.

For help please see the discussion group, or the IRC channel #voldemort. Bugs and feature requests can be filed on Google Code.

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