Struct PqAdcTables 

pub struct PqAdcTables { /* private fields */ }

Per-(query, metric) precomputed ADC lookup tables built from a ProductQuantizer.

Build once with ProductQuantizer::build_query_tables, then score many PqCodes against it via PqAdcTables::distance without rebuilding the M × K table per call.

Row m of the internal table holds the distances from query subvector q_m to each of the K centroids of codebook m, packed row-major. For DistanceMetric::Euclidean the row holds squared L2 values (so they sum decomposably across subvectors); PqAdcTables::distance takes sqrt of the total exactly once for Euclidean.

Implementations

impl PqAdcTables

pub fn distance(&self, code: &PqCode) -> Result<f32>

Score a single PqCode against the prepared tables.

The returned value matches Quantizer::distance for the same (query, code, metric) — for DistanceMetric::Euclidean the table holds squared L2 per subvector and this method sqrts the sum exactly once; the other supported metrics (DotProduct, Manhattan) sum directly.

Errors

Returns IqdbError::DimensionMismatch if code was produced by a ProductQuantizer with a different M or trained dim — typically the same quantizer that built the tables.

pub fn metric(&self) -> DistanceMetric

The metric these tables were built for.

pub fn n_subvectors(&self) -> usize

The number of subvectors M.

pub fn n_centroids(&self) -> usize

The number of centroids per subvector codebook K.

pub fn dim(&self) -> usize

The trained dimension these tables were built against.

Trait Implementations

impl Clone for PqAdcTables

fn clone(&self) -> PqAdcTables

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for PqAdcTables

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

Formats the value using the given formatter.