Trait CompressionStrategy

pub trait CompressionStrategy:
    Send
    + Sync
    + Debug {
    // Required methods
    fn create_block_compressor(
        &self,
        field: &Field,
        data: &DataBlock,
    ) -> Result<(Box<dyn BlockCompressor>, ArrayEncoding)>;
    fn create_per_value(
        &self,
        field: &Field,
        data: &DataBlock,
    ) -> Result<Box<dyn PerValueCompressor>>;
    fn create_miniblock_compressor(
        &self,
        field: &Field,
        data: &DataBlock,
    ) -> Result<Box<dyn MiniBlockCompressor>>;
}

A trait to pick which compression to use for given data

There are several different kinds of compression.

• Block compression is the most generic, but most difficult to use efficiently
• Per-value compression results in either a fixed width data block or a variable width data block. In other words, there is some number of bits per value. In addition, each value should be independently decompressible.
• Mini-block compression results in a small block of opaque data for chunks of rows. Each block is somewhere between 0 and 16KiB in size. This is used for narrow data types (both fixed and variable length) where we can fit many values into an 16KiB block.

Required Methods

fn create_block_compressor( &self, field: &Field, data: &DataBlock, ) -> Result<(Box<dyn BlockCompressor>, ArrayEncoding)>

Create a block compressor for the given data

fn create_per_value( &self, field: &Field, data: &DataBlock, ) -> Result<Box<dyn PerValueCompressor>>

Create a per-value compressor for the given data

fn create_miniblock_compressor( &self, field: &Field, data: &DataBlock, ) -> Result<Box<dyn MiniBlockCompressor>>

Create a mini-block compressor for the given data

Implementors

impl CompressionStrategy for CoreArrayEncodingStrategy