A wide-column-store (or extensible record stores) is a type of NoSQL database. It uses tables, rows, and columns, but unlike a relational database, the names and format of the column can vary from row to row in the same table.
A wide-column store can be interpreted as a two-dimensional key-value store.
Wide-column stores' 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.
In Wide-column, all data is stored in a row-by-row fashion, such that the columns for a given row are stored together, rather than each column being stored separately.