Struct DictEncoding 

pub struct DictEncoding { /* private fields */ }

A dictionary-encoded string column.

Unique string values are assigned compact u32 codes in sorted order (via BTreeMap), guaranteeing deterministic encoding across runs.

Implementations

impl DictEncoding

pub fn encode(data: &[String]) -> Self

Build a dictionary encoding from a string column.

Unique values are sorted (BTreeMap natural ordering) and assigned consecutive codes starting from 0.

pub fn decode(&self) -> Vec<String>

Decode back to the original string values.

pub fn lookup(&self, value: &str) -> Option<u32>

Look up the code for a string value.

pub fn cardinality(&self) -> usize

Number of unique values in the dictionary.

pub fn codes(&self) -> &[u32]

Get the encoded codes slice.

pub fn dict(&self) -> &BTreeMap<String, u32>

Get the dictionary mapping (sorted).

pub fn reverse(&self) -> &[String]

Get the reverse lookup table (code -> string).

Trait Implementations

impl Clone for DictEncoding

fn clone(&self) -> DictEncoding

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for DictEncoding

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

Formats the value using the given formatter.