2010/9/20

Bigtable has achieved several goals: wide applicability, scalability, high performance, and high availability.

In many ways, Bigtable resembles a database: it shares many implementation strategies with databases.

Bigtable does not support a full relational data model; instead, it provides clients with a simple data model that supports dynamic control over data layout and format, and allows clients to reason about the locality properties of the data represented in the underlying storage.

A bigtable is a sparse, distributed, persistent multi-dimensional sorted map.

1）Row

The row keys in the table are arbitrary string(64kb), and are maintained by lexicographic order.

2) Column Families

Column keys are grouped into sets called column families, which form the basic unit of access control.

3) Timestamps

Each cell in a Bigtable can contain multiple versions of the same data; these versions are indexed by timestamp. Bigtable timestamps are 64-bit integers.

IMPLEMENTATION

The Bigtable implementation has three major components: a library that is linked into every client, one master server, and many tablet servers.