Struct parquet::encoding::DictEncoder [−][src]
pub struct DictEncoder<T: DataType> { /* fields omitted */ }
Dictionary encoder. The dictionary encoding builds a dictionary of values encountered in a given column. The dictionary page is written first, before the data pages of the column chunk.
Dictionary page format: the entries in the dictionary - in dictionary order - using the plain encoding.
Data page format: the bit width used to encode the entry ids stored as 1 byte (max bit width = 32), followed by the values encoded using RLE/Bit packed described above (with the given bit width).
Methods
impl<T: DataType> DictEncoder<T>
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impl<T: DataType> DictEncoder<T>
pub fn new(desc: ColumnDescPtr, mem_tracker: MemTrackerPtr) -> Self
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pub fn new(desc: ColumnDescPtr, mem_tracker: MemTrackerPtr) -> Self
Creates new dictionary encoder.
pub fn num_entries(&self) -> usize
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pub fn num_entries(&self) -> usize
Returns number of unique entries in the dictionary.
pub fn write_dict(&self) -> Result<ByteBufferPtr>
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pub fn write_dict(&self) -> Result<ByteBufferPtr>
Writes out the dictionary values with PLAIN encoding in a byte buffer, and return the result.
pub fn write_indices(&mut self) -> Result<ByteBufferPtr>
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pub fn write_indices(&mut self) -> Result<ByteBufferPtr>
Writes out the dictionary values with RLE encoding in a byte buffer, and return the result.
Trait Implementations
impl<T: DataType> Encoder<T> for DictEncoder<T>
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impl<T: DataType> Encoder<T> for DictEncoder<T>
fn put(&mut self, values: &[T::T]) -> Result<()>
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fn put(&mut self, values: &[T::T]) -> Result<()>
Encodes data from values
.
fn encoding(&self) -> Encoding
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fn encoding(&self) -> Encoding
Returns the encoding type of this encoder.
fn flush_buffer(&mut self) -> Result<ByteBufferPtr>
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fn flush_buffer(&mut self) -> Result<ByteBufferPtr>
Flushes the underlying byte buffer that's being processed by this encoder, and return the immutable copy of it. This will also reset the internal state. Read more
Auto Trait Implementations
impl<T> !Send for DictEncoder<T>
impl<T> !Send for DictEncoder<T>
impl<T> !Sync for DictEncoder<T>
impl<T> !Sync for DictEncoder<T>