Relational queries #

Cross-document navigation: nested sub-object queries, semi-joins against other collections, bounded graph traversal, and graph projections of the hit set.

• Nested query — match within ONE array element (the cross-element pitfall)
• Join query — semi-join against another collection (server-side)
• Traverse query — bounded graph walk over a relation edge field
• Graph projection block — render the hit set as nodes and edges

No SQL twins: relations (nested, join, traverse, the graph block) stay DSL-side in the current SQL subset — JOIN between collections is not in the SQL M1 grammar yet.