Trait ChunkReader

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pub trait ChunkReader:
    Length
    + Send
    + Sync {
    type T: Read;

    // Required methods
    fn get_read(&self, start: u64) -> Result<Self::T>;
    fn get_bytes(&self, start: u64, length: usize) -> Result<Bytes>;
}

Expand description

Generates Readers to read chunks of a Parquet data source.

The Parquet reader uses ChunkReader to access Parquet data, allowing multiple decoders to read concurrently from different locations in the same file.

The trait functions both as a reader and a factory for readers.

random access via Self::get_bytes
sequential access via the reader returned via factory method Self::get_read

§Provided Implementations

File for reading from local file system
[Bytes] for reading from an in-memory buffer

User provided implementations can implement more sophisticated behaviors such as on-demand buffering or scan sharing.

Required Associated Types§

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type T: Read

The concrete type of reader returned by this trait

Required Methods§

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fn get_read(&self, start: u64) -> Result<Self::T>

Get a Read instance starting at the provided file offset

Returned readers follow the model of File::try_clone where mutations of one reader affect all readers. Thus subsequent or concurrent calls to Self::get_read or Self::get_bytes may cause side-effects on previously returned readers. Callers of get_read should take care to avoid race conditions.

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