A distributed data store is a

computer network A computer network is a collection of communicating computers and other devices, such as printers and smart phones. In order to communicate, the computers and devices must be connected by wired media like copper cables, optical fibers, or b ...

where information is stored on more than one

node In general, a node is a localized swelling (a "knot") or a point of intersection (a vertex). Node may refer to: In mathematics * Vertex (graph theory), a vertex in a mathematical graph *Vertex (geometry), a point where two or more curves, lines ...

, often in a replicated fashion. It is usually specifically used to refer to either a

distributed database A distributed database is a database in which data is stored across different physical locations. It may be stored in multiple computers located in the same physical location (e.g. a data centre); or maybe dispersed over a computer network, netwo ...

where users store information on a ''number of nodes'', or a

in which users store information on a ''number of peer network nodes''.

Distributed databases

Distributed database A distributed database is a database in which data is stored across different physical locations. It may be stored in multiple computers located in the same physical location (e.g. a data centre); or maybe dispersed over a computer network, netwo ...

s are usually non-relational databases that enable a quick access to data over a large number of nodes. Some distributed databases expose rich query abilities while others are limited to a key-value store semantics. Examples of limited distributed databases are

Google Google LLC (, ) is an American multinational corporation and technology company focusing on online advertising, search engine technology, cloud computing, computer software, quantum computing, e-commerce, consumer electronics, and artificial ...

's Bigtable, which is much more than a

distributed file system A clustered file system (CFS) is a file system which is shared by being simultaneously Mount (computing), mounted on multiple Server (computing), servers. There are several approaches to computer cluster, clustering, most of which do not emplo ...

or a peer-to-peer network,

Amazon Amazon most often refers to: * Amazon River, in South America * Amazon rainforest, a rainforest covering most of the Amazon basin * Amazon (company), an American multinational technology company * Amazons, a tribe of female warriors in Greek myth ...

's Dynamo and Microsoft Azure Storage. As the ability of arbitrary querying is not as important as the availability, designers of distributed data stores have increased the latter at an expense of consistency. But the high-speed read/write access results in reduced consistency, as it is not possible to guarantee both

consistency In deductive logic, a consistent theory is one that does not lead to a logical contradiction. A theory T is consistent if there is no formula \varphi such that both \varphi and its negation \lnot\varphi are elements of the set of consequences ...

and availability on a partitioned network, as stated by the

CAP theorem In database theory, the CAP theorem, also named Brewer's theorem after computer scientist Eric Brewer (scientist), Eric Brewer, states that any distributed data store can provide at most Inconsistent triad, two of the following three guarantees: ; ...

Peer network node data stores

In peer network data stores, the user can usually reciprocate and allow other users to use their computer as a storage node as well. Information may or may not be accessible to other users depending on the design of the network. Most

peer-to-peer Peer-to-peer (P2P) computing or networking is a distributed application architecture that partitions tasks or workloads between peers. Peers are equally privileged, equipotent participants in the network, forming a peer-to-peer network of Node ...

networks do not have distributed data stores in that the user's data is only available when their node is on the network. However, this distinction is somewhat blurred in a system such as

BitTorrent BitTorrent is a Protocol (computing), communication protocol for peer-to-peer file sharing (P2P), which enables users to distribute data and electronic files over the Internet in a Decentralised system, decentralized manner. The protocol is d ...

, where it is possible for the originating node to go offline but the content to continue to be served. Still, this is only the case for individual files requested by the redistributors, as contrasted with networks such as Hyphanet, Winny, Share and Perfect Dark where any node may be storing any part of the files on the network. Distributed data stores typically use an error detection and correction technique. Some distributed data stores (such as Parchive over NNTP) use forward error correction techniques to recover the original file when parts of that file are damaged or unavailable. Others try again to download that file from a different mirror.

Examples

Distributed non-relational databases

Peer network node data stores

* Blockchain (database) * Chord project *

Freenet Hyphanet (until mid-2023: Freenet) is a peer-to-peer platform for censorship-resistant, Anonymity application, anonymous communication. It uses a decentralized distributed data store to keep and deliver information, and has a suite of free soft ...

* GNUnet * IPFS * Mnet * Napster * NNTP (the distributed data storage protocol used for

Usenet Usenet (), a portmanteau of User's Network, is a worldwide distributed discussion system available on computers. It was developed from the general-purpose UUCP, Unix-to-Unix Copy (UUCP) dial-up network architecture. Tom Truscott and Jim Elli ...

news) * Unity, of the software Perfect Dark * Share * Siacoin * DeNet * Storage@home * Tahoe-LAFS * Winny * ZeroNet

References

{{Reflist Data management ja:分散ファイルシステム#分散データストア

Distributed databases

Peer network node data stores

Examples

Distributed non-relational databases

Peer network node data stores

See also

References