The increase in the size and in the semantic heterogeneity of database schemas bring new requirements for users querying and searching structured data.
At the center of this discussion is the semantic gap between users and databases, which becomes more central as the scale and complexity of the data grows.
Similarly, Tran et al.[4] defines it as "search approaches, which do not require users to know the schema underlying the data".
The development of approaches to support natural language interfaces (NLI) over databases have aimed towards the goal of schema-agnostic queries.
Complementarily, some approaches based on keyword search have targeted keyword-based queries which express more complex information needs.
Most of schema-agnostic query systems have been investigated in the context of Natural Language Interfaces over databases or over the Semantic Web.