Struct IvfPqConfig 

pub struct IvfPqConfig {
    pub nlist: usize,
    pub nprobe: usize,
    pub pq_m: usize,
    pub pq_k: usize,
    pub max_iter: usize,
    pub residual: bool,
}

Configuration for IVF-PQ index construction and search.

Fields

nlist: usize

Number of coarse Voronoi cells (inverted lists). Rule of thumb: sqrt(n) for balanced recall/speed. Default 256.

nprobe: usize

Cells probed per query. Higher = better recall, more compute. nprobe=1 is ANN; nprobe=nlist is exact. Default 8.

pq_m: usize

PQ sub-vector count M. Must divide dim. Default 8.

pq_k: usize

PQ centroids per sub-space K. Must be ≤ 256 (u8 codes). Default 256.

max_iter: usize

k-means max iterations for both coarse and PQ training. Default 25.

residual: bool

Residual PQ: train PQ on per-cluster residuals (vec - coarse_centroid) instead of raw vectors. Same storage cost, ~2-4pp better recall@10. Default false (backward-compatible).

Implementations

impl IvfPqConfig

pub fn for_dim(dim: usize) -> IvfPqConfig

Derive sensible defaults from vector dimensionality.

pub fn for_dataset(dim: usize, n_vectors: usize) -> IvfPqConfig

Derive sensible defaults from both dimensionality and dataset size.

nlist scales with sqrt(n_vectors) so each cluster gets ~4 vectors on average. Clamped to [16, 1024] to avoid degenerate configs on tiny or huge datasets.

pub fn with_residual(self) -> IvfPqConfig

Enable residual PQ — train on per-cluster residuals for better recall at same storage.

Trait Implementations

impl Clone for IvfPqConfig

fn clone(&self) -> IvfPqConfig

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for IvfPqConfig

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

Formats the value using the given formatter.

impl Default for IvfPqConfig

fn default() -> IvfPqConfig

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for IvfPqConfig

fn deserialize<__D>( __deserializer: __D, ) -> Result<IvfPqConfig, <__D as Deserializer<'de>>::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Serialize for IvfPqConfig

fn serialize<__S>( &self, __serializer: __S, ) -> Result<<__S as Serializer>::Ok, <__S as Serializer>::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.