Crate rust_diskann 

DiskAnn (generic over anndists::Distance<f32>)

A minimal, on-disk, DiskANN-like library that:

• Builds a Vamana-style graph (greedy + α-pruning) in memory
• Writes vectors + fixed-degree adjacency to a single file
• Memory-maps the file for low-overhead reads
• Is generic over any Distance from anndists (L2, Cosine, Hamming, Dot, …)

Example

use anndists::dist::{DistL2, DistCosine};
use diskann_rs::{DiskANN, DiskAnnParams};

// Build a new index from vectors, using L2 and default params
let vectors = vec![vec![0.0; 128]; 1000];
let index = DiskANN::<DistL2>::build_index_default(&vectors, DistL2{}, "index.db").unwrap();

// Or with custom params
let index2 = DiskANN::<DistCosine>::build_index_with_params(
    &vectors,
    DistCosine{},
    "index_cos.db",
    DiskAnnParams { max_degree: 48, ..Default::default() },
).unwrap();

// Search the index
let query = vec![0.0; 128];
let neighbors = index.search(&query, 10, 64);

// Open later (provide the same distance type)
let _reopened = DiskANN::<DistL2>::open_index_default_metric("index.db").unwrap();

File Layout

[ metadata_len:u64 ][ metadata (bincode) ][ padding up to vectors_offset ] [ vectors (num * dim * f32) ][ adjacency (num * max_degree * u32) ]

vectors_offset is a fixed 1 MiB gap by default.

Structs

DiskANN

Main struct representing a DiskANN index (generic over distance)

DiskAnnParams

Optional bag of knobs if you want to override just a few.

Enums

DiskAnnError

Custom error type for DiskAnnRS operations

Constants

DISKANN_DEFAULT_ALPHA

DISKANN_DEFAULT_BUILD_BEAM

DISKANN_DEFAULT_MAX_DEGREE

Defaults for in-memory DiskANN builds