Struct IndexStats 

pub struct IndexStats {
    pub n_vectors: usize,
    pub memory_bytes: usize,
    pub disk_bytes: Option<usize>,
    pub index_type: &'static str,
    pub extra: Option<HashMap<String, String>>,
}

A runtime snapshot of an index’s state.

Returned by crate::IndexCore::stats. The first four fields are the shared shape; extra is where index-specific counters live (for example, a tombstone count, or an HNSW layer histogram) without cluttering the trait. Construct one with the public fields directly, or start from IndexStats::default and override only what you have.

disk_bytes is Option because purely in-memory indexes have nothing on disk — they report None, not zero. An index that does spill to disk reports the on-disk footprint in bytes.

extra is Option (not a bare HashMap) so an implementer with no per-kind counters reports None without allocating an empty HashMap on every stats() call. The default value is None. A typical dashboard reads n_vectors, memory_bytes, and index_type without touching extra; the occasional inspector that needs the per-kind detail unwraps the Option.

Examples

use iqdb_index::IndexStats;

let stats = IndexStats {
    n_vectors: 42,
    memory_bytes: 4_096,
    index_type: "flat",
    ..IndexStats::default()
};

assert_eq!(stats.n_vectors, 42);
assert_eq!(stats.memory_bytes, 4_096);
assert_eq!(stats.disk_bytes, None);
assert_eq!(stats.index_type, "flat");
assert!(stats.extra.is_none());

Fields

n_vectors: usize

The number of vectors currently searchable in the index.

Excludes tombstoned entries: a vector that has been crate::IndexCore::deleted is not counted here even if the implementation has not yet reclaimed its storage.

memory_bytes: usize

Approximate resident-memory footprint of the index, in bytes.

A best-effort number for the in-memory state of the index. It is suitable for capacity dashboards, not for accounting.

disk_bytes: Option<usize>

On-disk footprint of the index in bytes, when the index persists to disk; None for purely in-memory indexes.

index_type: &'static str

A short, stable identifier for the index implementation (for example, "flat", "hnsw", "ivf"). Used in logs, metrics, and diagnostics.

extra: Option<HashMap<String, String>>

Index-specific counters that do not fit the shared shape.

Keys and values are both Strings so this map can carry any implementer’s bookkeeping (tombstone counts, build progress, graph statistics) without changing the trait surface. Wrapped in Option so implementers with no per-kind counters do not allocate an empty map on every stats() call.

Trait Implementations

impl Clone for IndexStats

fn clone(&self) -> IndexStats

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for IndexStats

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

Formats the value using the given formatter.

impl Default for IndexStats

fn default() -> IndexStats

Returns the “default value” for a type.

impl Eq for IndexStats

impl PartialEq for IndexStats

fn eq(&self, other: &IndexStats) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for IndexStats