Querying collections of tree-structured records in the presence of within-record referential constraints

In this paper, we consider a tree-structured data model used in many commercial databases like Dremel, F1, JSON. We define identity and referential constraints within each tree-structured record. The query language is a variant of SQL and flattening is used as an evaluation mechanism. We investigate querying in the presence of these constraints, and point out the challenges that arise from taking them into account during query evaluation.