[1] Google's Bigtable is one of the prototypical examples of a wide-column store.
[2] Wide-column stores such as Bigtable and Apache Cassandra are not column stores in the original sense of the term, since their two-level structures do not use a columnar data layout.
In genuine column stores, a columnar data layout is adopted such that each column is stored separately on disk.
However, each such column family typically contains multiple columns that are used together, similar to traditional relational database tables.
[citation needed] Notable wide-column stores [3] include: