Trait VectorSegmentBacking

Source

pub trait VectorSegmentBacking: Send + Sync {
    // Required methods
    fn len(&self) -> usize;
    fn dim(&self) -> usize;
    fn get_vector(&self, id: u32) -> Option<&[f32]>;
    fn get_surrogate(&self, id: u32) -> Option<u64>;

    // Provided methods
    fn is_empty(&self) -> bool { ... }
    fn prefetch(&self, _id: u32) { ... }
}

Expand description

Storage abstraction for HNSW vector data.

Two implementations coexist:

PlainMmapBacking: zero-copy mmap of a plaintext NDVS file (Origin).
PagedbBacking: encrypted segment read via pagedb (Lite, task 2a.2).

Implementations are responsible for vector retrieval; HNSW graph traversal makes no storage-level decisions.

§`Send + Sync` bound

The bound allows consumers to park the backing in an Arc<dyn VectorSegmentBacking> and dispatch across tasks. Lite will require this in task 2a.2.

§Return type for `get_vector`

-> Option<&[f32]> borrows from &self. This is correct for PlainMmapBacking (slice into mmap region lives as long as the backing) and for the planned PagedbBacking (which will hold a long-lived decrypted vector slab in a MmapView field on self).

If a future backing genuinely cannot return a &self-lifetime slice without copying, the signature can be changed to Cow<'_, [f32]> in a follow-up refactor. For now both known impls support the zero-copy path.