Struct PackedMask 

pub struct PackedMask { /* private fields */ }

A packed bitmask where each bit represents whether a row passes a filter.

Memory Efficiency

For 6M rows (lineitem at TPC-H SF 1):

• Vec<bool>: 6 MB per predicate
• PackedMask: 750 KB per predicate (8x reduction)

Performance Benefits

• Bitwise AND is a native SIMD instruction (vpand on x86, and on ARM)
• Better cache utilization due to reduced memory footprint
• Faster popcount using count_ones() intrinsic

Implementation

Bits are stored in little-endian order within each u64 word:

• Bit 0 of word 0 = row 0
• Bit 63 of word 0 = row 63
• Bit 0 of word 1 = row 64
• etc.

Implementations

impl PackedMask

pub fn new_all_set(len: usize) -> Self

Creates a new mask with all bits set (all rows pass).

pub fn new_all_clear(len: usize) -> Self

Creates a new mask with all bits clear (no rows pass).

pub fn len(&self) -> usize

Returns the number of rows this mask represents.

pub fn is_empty(&self) -> bool

Returns true if this mask is empty.

pub fn get(&self, index: usize) -> bool

Gets the value of the bit at the given index.

pub fn set(&mut self, index: usize, value: bool)

Sets the bit at the given index.

pub fn and_inplace(&mut self, other: &PackedMask)

Performs in-place bitwise AND with another mask.

This is the key operation for combining multiple predicates. Uses native bitwise AND which maps directly to SIMD instructions.

pub fn or_inplace(&mut self, other: &PackedMask)

Performs in-place bitwise OR with another mask.

This is used for combining multiple predicates in IN lists. Uses native bitwise OR which maps directly to SIMD instructions.

pub fn not(&self) -> PackedMask

Returns a new mask with all bits inverted.

This is used for NOT IN operations.

pub fn count_ones(&self) -> usize

Counts the number of set bits (rows that pass the filter).

Uses the count_ones() intrinsic which maps to hardware popcount.

pub fn from_bool_slice(slice: &[bool]) -> Self

Creates a packed mask from a boolean slice.

Used for compatibility with existing code during migration.

pub fn to_bool_vec(&self) -> Vec<bool>

Converts this packed mask back to a boolean vector.

Used for compatibility with existing code during migration.

pub fn words(&self) -> &[u64]

Returns a reference to the underlying word slice.

Trait Implementations

impl Clone for PackedMask

fn clone(&self) -> PackedMask

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for PackedMask

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

Formats the value using the given formatter.

impl PartialEq for PackedMask

fn eq(&self, other: &PackedMask) -> 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 Eq for PackedMask

impl StructuralPartialEq for PackedMask