Enum FusionKind 

#[non_exhaustive]
pub enum FusionKind {
    BtreeUnion,
    SortedKWayMerge,
    VidUidForkFirst,
    AnnRerank,
    Bm25Rrf,
}

Phase 5a-impl: per-type fusion strategy for LogicalPlan::FusedIndexScan.

#[non_exhaustive] so Phase 5b can add AnnRerank and Bm25Rrf without breaking downstream pattern-match exhaustiveness.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

BtreeUnion

Union of parent + fork-local BTree hits, deduped by VID.

SortedKWayMerge

k-way merge of pre-sorted parent + fork streams (ORDER BY).

VidUidForkFirst

Fork-first UID lookup; falls back to parent on miss. Used when a fork rebinds an external UID and queries must see the fork’s binding before the parent’s.

AnnRerank

Phase 5b — vector ANN rerank: top-k from primary’s index + top-k from fork-local index, merged and reranked by exact distance. Recall ≥ 95% per spec §8.2.

Bm25Rrf

Phase 5b — BM25 reciprocal rank fusion: ranked lists from primary’s and fork-local FTS indexes combined via standard RRF (score = sum 1 / (k_rrf + rank_i), k_rrf = 60).

Trait Implementations

impl Clone for FusionKind

fn clone(&self) -> FusionKind

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for FusionKind

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.