couchbase is one implemention of no-sql database. it can store key-value data or json document data.

it's origined from memcached and membased.

feature contains but not limited:

• high r/w performace & persistance it has high water level concept, usually data would be kept in ram for high performance, but once reach high water level, the data which is not active(not accessed recently) will be ejected to disk.

• scalable

• rebalance

• replicas

• shards