SQL-like query language and referential constraints on tree-structured data

Abstract

In this paper we investigate within-record referential constraints on tree-structured data. We consider an SQL-like query language such that the one used in Dremel and we call it tree-SQL. We show how to define and process a query in tree-SQL in the presence of referential constraints. We give the semantics of tree-SQL via flattening and show how to produce equivalent semantics using the notion of tree-expansion of a query in the presence of referential constraints.