Struct ColumnGroupAffinity 

pub struct ColumnGroupAffinity {
    pub type_groups: HashMap<ColumnType, Vec<ColumnId>>,
    pub access_frequency: HashMap<ColumnId, u64>,
    pub null_density: HashMap<ColumnId, f64>,
}

Column group affinity for compression optimization

Groups columns by:

1. Type compatibility (all Int64 together for SIMD)
2. Access correlation (co-accessed columns together)
3. Null density (sparse columns separate)

Fields

type_groups: HashMap<ColumnType, Vec<ColumnId>>

Columns grouped by type for SIMD optimization

access_frequency: HashMap<ColumnId, u64>

Access frequency per column (for hot/cold separation)

null_density: HashMap<ColumnId, f64>

Null density per column (0.0 = never null, 1.0 = always null)

Implementations

impl ColumnGroupAffinity

pub fn from_trie(trie: &PathTrie) -> Self

Create from a path trie

pub fn record_access(&mut self, column_id: ColumnId)

Record a column access (for access correlation)

pub fn update_null_density( &mut self, column_id: ColumnId, null_count: u64, total_count: u64, )

Update null density for a column

pub fn simd_groups(&self) -> Vec<(ColumnType, Vec<ColumnId>)>

Get columns suitable for SIMD processing (fixed-size, same type)

pub fn sparse_columns(&self, threshold: f64) -> Vec<ColumnId>

Get sparse columns (null_density > threshold)

pub fn hot_columns(&self, n: usize) -> Vec<ColumnId>

Get hot columns (top N by access frequency)

Trait Implementations

impl Clone for ColumnGroupAffinity

fn clone(&self) -> ColumnGroupAffinity

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for ColumnGroupAffinity

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

Formats the value using the given formatter.