Queryja

Queryja is a hypothetical cross-model query language designed to unify data retrieval across JSON-like documents, relational tables, and graph structures. It is described here as a conceptual tool used in data interoperability research and education to illustrate how a single query language could operate over diverse data stores.

The design goals of queryja include declarative syntax, type safety, and streaming execution. It supports path expressions for navigating nested data, pattern matching for graph-like structures, and standard aggregations. A typical query consists of a data source specification, a projection, and optional filters, joins, and groupings. For example, a simple query might retrieve the names of users over age 18 from a users collection, while a more advanced query could join user records with profile and order data to compute total spend.

Queryja is described as blending SQL-inspired elements with graph-oriented constructs, enabling both tabular and relationship-aware querying. Implementations are largely experimental, including toy interpreters and educational notebooks, and there is no single canonical specification.

Common use cases include data integration pipelines, API gateways that merge data from multiple services, and teaching environments that illustrate cross-model querying. The concept has attracted attention for its potential to reduce data access friction when working with heterogeneous stores, though it also faces criticism for complexity and a lack of agreed-upon semantics, which can hinder practical adoption. Proponents argue that a unified query abstraction could streamline data access across diverse data architectures.