- validation-prototypes/custom-operator/: NeighborExpand toy operator
with paired ExtensionPlanner + custom QueryPlanner via
SessionStateBuilder::with_query_planner
- writeup at .context/experiments/custom-operator.md: 5 probes
(round-trip, EXPLAIN, predicate guard, composition with Filter +
Aggregate, BaselineMetrics) \u2014 all pass; ~250 LoC integration
footprint; no unsafe; no internal API access
- finding: \u00a75.3 is achievable on DF 52.5 as written; deltas are
doc-shaped (predicate push-down opt-in, statistics requirement,
Partitioning override)
- exclude validation-prototypes/ and merge-insert-cas-repro from the main
workspace so the nested cargo workspace can use its own pin set
- add validation-prototypes/{factorized-batches,custom-lance-index}/
scratch crates (never merged to main; long-lived branch only)
- exp 1.1 — factorized batches through DataFusion ops: writeup at
.context/experiments/factorized-batches.md (5 cells × 8 ops; all
scalar-keyed ops accept List<UInt64> input, UNNEST via CROSS JOIN
fails in DF 52.5)
- exp 1.2 — custom Lance index plugin from outside lance: writeup at
.context/experiments/custom-lance-index.md (5 probes; transaction
surface is open, SCALAR_INDEX_PLUGIN_REGISTRY is closed → hard
blocker for MR-737 §5.4; recommends upstream path or external-index
path)
