Struct ZoneMapsFieldEncoder

pub struct ZoneMapsFieldEncoder { /* private fields */ }

A field encoder that creates zone maps for the data it encodes

This encoder will create zone maps for the data it encodes. The zone maps are created by dividing the data into zones of a fixed size and calculating the min/max values for each zone. The zone maps are then encoded as metadata.

This metadata can be used by the reader to skip over zones that don’t contain data that matches the query.

Implementations

impl ZoneMapsFieldEncoder

pub fn try_new( items_encoder: Box<dyn FieldEncoder>, items_type: DataType, rows_per_map: u32, ) -> Result<Self>

Trait Implementations

impl FieldEncoder for ZoneMapsFieldEncoder

fn maybe_encode( &mut self, array: ArrayRef, external_buffers: &mut OutOfLineBuffers, repdef: RepDefBuilder, row_number: u64, ) -> Result<Vec<EncodeTask>>

Buffer the data and, if there is enough data in the buffer to form a page, return an encoding task to encode the data.

fn flush( &mut self, external_buffers: &mut OutOfLineBuffers, ) -> Result<Vec<EncodeTask>>

Flush any remaining data from the buffers into encoding tasks

fn finish( &mut self, external_buffers: &mut OutOfLineBuffers, ) -> BoxFuture<'_, Result<Vec<EncodedColumn>>>

Finish encoding and return column metadata

fn num_columns(&self) -> u32

The number of output columns this encoding will create