N-Tier Soft Set Data Model: An Approach to Combine the Logicality of SQL and the Flexibility of NoSQL

Table 1

Comparison of data models.

	Relational	Key-value	Column family	Document	Graph	NTSS
Strict algebra basis	Yes	No	No	No	Yes	Yes
Completeness and consistency	Strong	Weak	Weak	Weak	Strong	Weak (but with native cardinality constraints)
Query expressiveness	Strong	Unidirectional	Multilevel unidirectional	Multilevel unidirectional	Strong	Strong
Data self-descriptive	No	Weak	Strong	Strong	Strong	Strong
Distributed support	Difficult	Easy	Easy	Easy	Difficult	Easy
Schema flexibility	Pre-defined rigid schema	Schemaless	Schemaless	Schemaless	Schemaless	Schemaless
Connecting data	Difficult	Difficult	Difficult	Difficult	Easy	Easy
Dependency on external indexes	Strong	Weak	Medium	Medium	Medium	No