Struct LowCardinality 

pub struct LowCardinality;

A strategy for encoding values that are often repeated.

This can be shockingly efficient when there are just a few values for e.g. a string field.

Trait Implementations

impl Clone for LowCardinality

fn clone(&self) -> LowCardinality

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for LowCardinality

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

Formats the value using the given formatter.

impl Default for LowCardinality

fn default() -> LowCardinality

Returns the “default value” for a type.

impl<const N: usize, T: Encode + Clone + Hash + Eq> EncodingStrategy<[T; N]> for LowCardinality

type Context = CacheContext<[T; N]>

The conext (i.e. probability model) for this encoding strategy applied to this type.

fn encode<W: Write>( value: &[T; N], writer: &mut Writer<W>, ctx: &mut Self::Context, ) -> Result<(), Error>

Encode the value with this strategy.

fn decode<R: Read>( reader: &mut Reader<R>, ctx: &mut Self::Context, ) -> Result<[T; N], Error>

Decode the value using this strategy.

fn millibits(value: &T, ctx: &mut Self::Context) -> Option<usize>

Estimate the size of the encoded value using this stratgy.

impl<T> EncodingStrategy<Option<T>> for LowCardinality

where LowCardinality: EncodingStrategy<T>,

type Context = LowContext<<LowCardinality as EncodingStrategy<T>>::Context>

The conext (i.e. probability model) for this encoding strategy applied to this type.

fn encode<W: Write>( value: &Option<T>, writer: &mut Writer<W>, ctx: &mut Self::Context, ) -> Result<(), Error>

Encode the value with this strategy.

fn decode<R: Read>( reader: &mut Reader<R>, ctx: &mut Self::Context, ) -> Result<Option<T>, Error>

Decode the value using this strategy.

fn millibits(value: &T, ctx: &mut Self::Context) -> Option<usize>

Estimate the size of the encoded value using this stratgy.

impl<T> EncodingStrategy<Option<T>> for LowCardinality

where LowCardinality: EncodingStrategy<T>,

type Context = LowContext<<LowCardinality as EncodingStrategy<T>>::Context>

The conext (i.e. probability model) for this encoding strategy applied to this type.

fn encode<E: EntropyCoder>( value: &Option<T>, writer: &mut E, ctx: &mut Self::Context, )

Encode the value with this strategy.

fn decode<D: EntropyDecoder>( reader: &mut D, ctx: &mut Self::Context, ) -> Result<Option<T>, Error>

Decode the value using this strategy.

impl EncodingStrategy<String> for LowCardinality

type Context = CacheContext<String>

The conext (i.e. probability model) for this encoding strategy applied to this type.

fn encode<W: Write>( value: &String, writer: &mut Writer<W>, ctx: &mut Self::Context, ) -> Result<(), Error>

Encode the value with this strategy.

fn decode<R: Read>( reader: &mut Reader<R>, ctx: &mut Self::Context, ) -> Result<String, Error>

Decode the value using this strategy.

fn millibits(value: &T, ctx: &mut Self::Context) -> Option<usize>

Estimate the size of the encoded value using this stratgy.

impl EncodingStrategy<String> for LowCardinality

type Context = CacheContext<String>

The conext (i.e. probability model) for this encoding strategy applied to this type.

fn encode<E: EntropyCoder>( value: &String, writer: &mut E, ctx: &mut Self::Context, )

Encode the value with this strategy.

fn decode<D: EntropyDecoder>( reader: &mut D, ctx: &mut Self::Context, ) -> Result<String, Error>

Decode the value using this strategy.

impl<T> EncodingStrategy<Vec<T>> for LowCardinality

where T: Encode, LowCardinality: EncodingStrategy<T>,

type Context = (<usize as Encode>::Context, <LowCardinality as EncodingStrategy<T>>::Context)

The conext (i.e. probability model) for this encoding strategy applied to this type.

fn encode<W: Write>( value: &Vec<T>, writer: &mut Writer<W>, ctx: &mut Self::Context, ) -> Result<(), Error>

Encode the value with this strategy.

fn decode<R: Read>( reader: &mut Reader<R>, ctx: &mut Self::Context, ) -> Result<Vec<T>, Error>

Decode the value using this strategy.

fn millibits(value: &T, ctx: &mut Self::Context) -> Option<usize>

Estimate the size of the encoded value using this stratgy.

impl<T> EncodingStrategy<Vec<T>> for LowCardinality

where T: Encode, LowCardinality: EncodingStrategy<T>,

type Context = (<usize as Encode>::Context, <LowCardinality as EncodingStrategy<T>>::Context)

The conext (i.e. probability model) for this encoding strategy applied to this type.

fn encode<E: EntropyCoder>( value: &Vec<T>, writer: &mut E, ctx: &mut Self::Context, )

Encode the value with this strategy.

fn decode<D: EntropyDecoder>( reader: &mut D, ctx: &mut Self::Context, ) -> Result<Vec<T>, Error>

Decode the value using this strategy.

impl EncodingStrategy<Vec<u8>> for LowCardinality

type Context = CacheContext<Vec<u8>>

The conext (i.e. probability model) for this encoding strategy applied to this type.

fn encode<W: Write>( value: &Vec<u8>, writer: &mut Writer<W>, ctx: &mut Self::Context, ) -> Result<(), Error>

Encode the value with this strategy.

fn decode<R: Read>( reader: &mut Reader<R>, ctx: &mut Self::Context, ) -> Result<Vec<u8>, Error>

Decode the value using this strategy.

fn millibits(value: &T, ctx: &mut Self::Context) -> Option<usize>

Estimate the size of the encoded value using this stratgy.

impl EncodingStrategy<Vec<u8>> for LowCardinality

type Context = CacheContext<Vec<u8>>

The conext (i.e. probability model) for this encoding strategy applied to this type.

fn encode<E: EntropyCoder>( value: &Vec<u8>, writer: &mut E, ctx: &mut Self::Context, )

Encode the value with this strategy.

fn decode<D: EntropyDecoder>( reader: &mut D, ctx: &mut Self::Context, ) -> Result<Vec<u8>, Error>

Decode the value using this strategy.

impl EncodingStrategy<u64> for LowCardinality

type Context = CacheContext<u64>

The conext (i.e. probability model) for this encoding strategy applied to this type.

fn encode<W: Write>( value: &u64, writer: &mut Writer<W>, ctx: &mut Self::Context, ) -> Result<(), Error>

Encode the value with this strategy.

fn decode<R: Read>( reader: &mut Reader<R>, ctx: &mut Self::Context, ) -> Result<u64, Error>

Decode the value using this strategy.

fn millibits(value: &T, ctx: &mut Self::Context) -> Option<usize>

Estimate the size of the encoded value using this stratgy.

impl EncodingStrategy<u64> for LowCardinality

type Context = CacheContext<u64>

The conext (i.e. probability model) for this encoding strategy applied to this type.

fn encode<E: EntropyCoder>(value: &u64, writer: &mut E, ctx: &mut Self::Context)

Encode the value with this strategy.

fn decode<D: EntropyDecoder>( reader: &mut D, ctx: &mut Self::Context, ) -> Result<u64, Error>

Decode the value using this strategy.

impl Hash for LowCardinality

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl Ord for LowCardinality

fn cmp(&self, other: &LowCardinality) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl PartialEq for LowCardinality

fn eq(&self, other: &LowCardinality) -> 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 PartialOrd for LowCardinality

fn partial_cmp(&self, other: &LowCardinality) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

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

Tests less than (for self and other) and is used by the < operator.

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

Tests less than or equal to (for self and other) and is used by the <= operator.

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

Tests greater than (for self and other) and is used by the > operator.

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

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl Copy for LowCardinality

impl Eq for LowCardinality

impl StructuralPartialEq for LowCardinality