A JSON document algebra for query optimization

Abstract

Due to the popularity of JSON, several systems have been developed that store data in collections of JSON documents. Each system has developed its own query language, sometimes in an ad-hoc manner. This makes difficult to formally define and analyze query optimization techniques. We propose an algebra tailored to JSON documents. First, we argue that JSON is different from nested relations and XML and therefore requires its own solution. Then, we propose an algebra on 3 levels: the first level defines operators to manipulate individual documents, providing an abstraction over different serializations. The second level provides operators over collections of JSON documents, while the third level defines also collection operators which are not primitive, but that enable direct and efficient implementation of data manipulation operations. We provide a number of properties of the algebraic operators which provide a solid basis for query optimization.