Apache HBase

Apache HBase is an open-source, strongly consistent distributed database designed to store record-oriented data across a scalable cluster of machines. HBase stores rows of data in tables that can be grouped into namespaces, and a table can belong to only one namespace at a time. Tables are split into groups of lexicographically adjacent rows called regions. By “lexicographically adjacent,” we mean that all rows in the table that sort between the region’s start row key and end row key are stored in the same region.

Regions are distributed across the cluster, hosted, and made available to clients by RegionServer processes. Regions are the physical mechanism used to shard and distribute the write and query load across the fleet of RegionServers. Regions are also non-overlapping: A single row key belongs to exactly one region at any point in time. Together with the special META table, a table’s regions effectively form a B-tree for the purposes of locating a row within a table.