[Retracted] Schema-Based Mapping Approach for Data Transformation to Enrich Semantic Web

Table 4

Data retrieval time comparison (data materialization).

Method	Join operations
	Self-Join (time in ms)	Equi-Join (time in ms)	Multitable M:N relations (time in ms)
Direct mapping	523	705	930
Augmented direct mapping	464	632	847
R2RML	407	568	721
RDB-RDF (proposed method)	361	437	615