Struct parquet::decoding::DictDecoder

pub struct DictDecoder<T: DataType> { /* fields omitted */ }

Dictionary decoder. The dictionary encoding builds a dictionary of values encountered in a given column. The dictionary is be stored in a dictionary page per column chunk. See DictEncoder for more information.

Implementations

impl<T: DataType> DictDecoder<T>

pub fn new() -> Self

Creates new dictionary decoder.

pub fn set_dict(&mut self, decoder: Box<dyn Decoder<T>>) -> Result<()>

Decodes and sets values for dictionary using decoder decoder.

Trait Implementations

impl<T: DataType> Decoder<T> for DictDecoder<T>

fn values_left(&self) -> usize

Number of values left in this decoder stream

fn set_data(&mut self, data: ByteBufferPtr, num_values: usize) -> Result<()>

Sets the data to decode to be data, which should contain num_values of values to decode.

fn get(&mut self, buffer: &mut [T::T]) -> Result<usize>

Consumes values from this decoder and write the results to buffer. This will try to fill up buffer.

fn encoding(&self) -> Encoding

Returns the encoding for this decoder.

fn get_spaced(
    &mut self,
    buffer: &mut [T::T],
    null_count: usize,
    valid_bits: &[u8]
) -> Result<usize>

Consume values from this decoder and write the results to buffer, leaving “spaces” for null values.