We've so far ignored one curious entity in the column family data structure-each RowKey seems to have a cell whose value is empty, and whose name consists purely of a clustering column value and a delimiter.
Recall that, in a CQL row, there is no requirement that any data column contain data. A row consisting purely of values for the primary key columns is entirely valid. CQL makes this possible by storing an extra cell any time a row is created or updated that acts as a placeholder indicating that there is a row in the clustering column encoded in the cell's name. Thus, the existence of the row is guaranteed even if there is no data column to be stored as a cell in that row.
