ID

R24

Status

Backlog

Bucket

cleanup

Priority

13

Theme

nodeid

Rooted-at-parent NodeId reference JOIN-projection emitter

(Title symbol re-anchored 2026-07-13 and again 2026-07-21: the original NodeIdReferenceField carrier was renamed by R50 to the column-shaped ChildField.ColumnReferenceField / CompositeColumnReferenceField pair, and R508 dissolved that pair into the single merged ChildField.ColumnBackedReferenceField carrying arity as a column count; the file keeps its slug as its own identity. The in-code deferral no longer carries a slug pointer: it anchors to this shape through its Rejection.StubKey.VariantClass key, a live class reference rather than a roadmap path.)

R50 shipped two of the three rooted shapes named in Variant-by-variant collapse → Single-hop emission, two shapes: rooted-at-child emission (FK-mirror, no JOIN, parent’s FK columns encode directly) and the classifier-side resolution for rooted-at-parent (phase g-B produces ChildField.ColumnReferenceField / CompositeColumnReferenceField with compaction = NodeIdEncodeKeys and a resolved joinPath). What did not ship is the matching emitter. The rooted-at-parent shape now surfaces as one build-time typed deferral regardless of arity, an improvement over the runtime UnsupportedOperationException stubs the original write-up described: since R508 merged the two carriers, GraphitronSchemaValidator.validateColumnBackedReferenceField rejects the NodeIdEncodeKeys compaction on ChildField.ColumnBackedReferenceField as deferred at every arity ahead of generation (the old TypeFetcherGenerator.STUBBED_VARIANTS stub entry retired with the composite class; the map is empty today), keyed by the merged class through its StubKey.VariantClass anchor.

R24 absorbs the remaining emitter work, expanded beyond its original framing:

  • Rooted-at-parent single-hop JOIN-with-projection ; the FK is one hop, but its source columns differ from the target NodeType’s keyColumns (e.g. the FK references the parent through a non-PK unique constraint, or the parent’s NodeId uses columns the FK doesn’t reach). The emitter brings the parent table into scope via JOIN, threads the carrier’s joinPath through $fields(), and projects encode<TypeName>(parent_alias.k1, ..., parent_alias.kN). This shape has a fixture in nodeidfixture (R50 phase g-B’s parent_node + child_ref tables) ready to drive execution-tier coverage as soon as the emitter lands.

  • Multi-hop FK and condition-join correlated-subquery emission ; the original R24 scope. Anything past one hop, or where the FK is replaced by a condition-join, wants a correlated subquery rooted at the parent, projecting the parent’s keyColumns under aliases. No fixture yet; the test surface grows when a real schema reaches the shape.

Both arities route through the one merged carrier (ChildField.ColumnBackedReferenceField with compaction = NodeIdEncodeKeys, columns 1..N); the differentiator is how the target columns are brought into scope (single-hop JOIN vs correlated subquery), not the carrier shape. The emitter switches on the resolved `joinPath’s shape.

Re-spec when a real schema reaches one of the shapes; pin the load-bearing structure (multi-hop path, condition-join path, non-mirroring FK) here before re-spec’ing. R50 (lift-nodeid-out-of-model, shipped) introduced the column-shaped carriers (since merged by R508 into ChildField.ColumnBackedReferenceField) with compaction = CallSiteCompaction.NodeIdEncodeKeys and the rooted-at-parent fixture in nodeidfixture (parent_node + child_ref); the changelog entry preserves the originating context.

Coordination with R40 (shipped)

R40 (argument-level @nodeId, Done; its item file is deleted, see the changelog) was the symmetric input-side feature: argument-level @nodeId decoding for both same-table (lookup) and FK-target (filter) shapes. Its column-backed reference-arg carriers live in ArgumentRef.java today (merged by R508 into ScalarArg.ColumnBackedReferenceArg). R24 and R40 thread the same joinPath: List<JoinStep> (R50 phase g-B) and share the parent_node + child_ref execution fixture, but they do not share emitter code (R24 = output-side encode emitter; R40 = input-side decode + filter projection). When R24 lands its JOIN-with-projection emitter, any joinPath threading helper that falls out may be worth lifting to a place the shipped input-side filter projection can also reach. The pathological FK-target input-side case remains separately filed as R57 (nodeid-fk-target-arg-join-translation).