Enum PostingFormat 

pub enum PostingFormat {
    HorizontalBP128,
    VerticalBP128,
    EliasFano,
    PartitionedEF,
    Roaring,
    OptP4D,
}

Posting list format selector

Variants

HorizontalBP128

Horizontal BP128 layout (fastest encoding + decoding with SIMD)

VerticalBP128

Vertical BP128 with bit-interleaved layout (optimal for SIMD scatter)

EliasFano

Elias-Fano for long posting lists

PartitionedEF

Partitioned Elias-Fano (very long lists, better compression)

Roaring

Roaring bitmap for very frequent terms

OptP4D

OptP4D (Optimized Patched Frame-of-Reference Delta) - optimal bit-width selection with exceptions

Implementations

impl PostingFormat

pub fn select(doc_count: usize, total_docs: usize) -> Self

Select optimal format based on posting list characteristics

Simplified format selection (based on benchmarks):

• Very frequent (>1% of corpus, >20K docs): Roaring (fastest iteration, set ops)
• Large (≥20K docs): Partitioned EF (best compression 15.9%)
• All other lists: HorizontalBP128 (fastest encoding + decoding with SIMD, optimal compression)

Note: HorizontalBP128 now has SIMD optimizations (NEON/SSE) and outperforms SIMD-BP128:

• Faster encoding (horizontal layout vs vertical bit-interleaved)
• Faster decoding with 64-bit unaligned reads (236K vs 199K ints/μs)
• Same compression ratio

Trait Implementations

impl Clone for PostingFormat

fn clone(&self) -> PostingFormat

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for PostingFormat

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

Formats the value using the given formatter.

impl PartialEq for PostingFormat

fn eq(&self, other: &PostingFormat) -> 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 Copy for PostingFormat

impl Eq for PostingFormat

impl StructuralPartialEq for PostingFormat