Key-value database systems¶
Key-value databases, also known as key value stores, store key/value pairs.
Database systems¶
Key/value database systems are e.g. Riak, Cassandra, Redis and MongoDB.
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GitHub |
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Docs |
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Application areas |
Session storage, Log data, Sensor data, CMS |
Georedundancy, high writing speed, democratic peer-to-peer (P2P) architecture, data with a defined lifetime |
Session Cache, Full Page Cache (FPC), Queues, Pub/Sub |
IoT, Mobile apps, CMS, 2d Index Internals, … |
Development language |
Erlang |
Java |
ANSI C |
C++ |
Licenses |
Apache License 2.0 |
Apache License 2.0 |
Redis Source Available License v2, Server-Side Public License v1 |
Server Side Public License |
Data model |
Essentially Key/value pair |
Column Family correspond to tables, keyspaces to databases; no logical structure, no scheme |
Keys are stored as strings, values as strings, hashes, lists, sets and sorted sets |
Flexible scheme with denormalised model |
Query language |
Keyfilter, MapReduce, Link walking, no ad hoc queries possible |
jQuery, MapReduce |
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Transactions, concurrency |
in-memory, asynchronous on disc with Append Only File Mode |
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Replication, skaling |
Multi-master replication |
SimpleStrategy, NetworkTopologyStrategy and OldNetworkTopologyStrategy |
Master-N-Slaves replication, Sharding using Consistent hash function |
Master-Slave replication, Auto-Sharding |
Remarks |
See also Scylla, a Cassandra-compatible reimplementation in C. |
See also: |
BSON with a maximum document size of 16 MB. |