Why many refer to Cassandra as a Column oriented database?

Question

Reading several papers and documents on internet, I found many contradictory information about the Cassandra data model. There are many which identify it as a column oriente

Answer 1

The most unambiguous term I have come across is wide-column store.

It is a kind of two-dimensional key-value store, where you use a row key and a column key to access data.

The main difference between this model and the relational ones (both row-oriented and column-oriented) is that the column information is part of the data.

This implies data can be sparse. That means different rows don't need to share the same column names nor number of columns. This enables semi-structured data or schema free tables.

You can think of wide-column stores as tables that can hold an unlimited number of columns, and thus are wide.

Here's a couple of links to back this up:

• This mongodb article
• This Datastax article mentions it too, although it classifies Cassandra as a key-value store.
• This db-engines article
• This 2013 article
• Wikipedia