Cassandra interview questions: Difference between Cassandra's schema and RDBMS schema?
The following table lists down the points that differentiate the schema of Cassandra from that of an RDBMS.
| S.N | RDBMS | Cassandra |
| 1 | RDBMS deals with structured data. | Cassandra deals with unstructured data. |
| 2 | It has a fixed schema. | Cassandra has a flexible schema. |
| 3 | In RDBMS, a table is an array of arrays. (ROW x COLUMN) | In Cassandra, a table is a list of “nested key-value pairs”. (ROW x COLUMN key x COLUMN value) |
| 4 | Database is the outermost container that contains data corresponding to an application. | Keyspace is the outermost container that contains data corresponding to an application. |
| 5 | Tables are the entities of a database. | Tables or column families are the entity of a keyspace. |
| 6 | Row is an individual record in RDBMS. | Row is a unit of replication in Cassandra. |
| 7 | Column represents the attributes of a relation. | Column is a unit of storage in Cassandra. |
| 8 | RDBMS supports the concepts of foreign keys, joins. | Relationships are represented using collections. |
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