[−][src]Struct parquet::encoding::DictEncoder
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).
Implementations
impl<T: DataType> DictEncoder<T>
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pub fn new(desc: ColumnDescPtr, mem_tracker: MemTrackerPtr) -> Self
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Creates new dictionary encoder.
pub fn is_sorted(&self) -> bool
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Returns true if dictionary entries are sorted, false otherwise.
pub fn num_entries(&self) -> usize
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Returns number of unique values (keys) in the dictionary.
pub fn dict_encoded_size(&self) -> usize
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Returns size of unique values (keys) in the dictionary, in bytes.
pub fn write_dict(&self) -> Result<ByteBufferPtr>
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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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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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Auto Trait Implementations
impl<T> !RefUnwindSafe for DictEncoder<T>
impl<T> !Send for DictEncoder<T>
impl<T> !Sync for DictEncoder<T>
impl<T> Unpin for DictEncoder<T> where
<T as DataType>::T: Unpin,
<T as DataType>::T: Unpin,
impl<T> !UnwindSafe for DictEncoder<T>
Blanket Implementations
impl<T> Any for T where
T: 'static + ?Sized,
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T: 'static + ?Sized,
impl<T> Borrow<T> for T where
T: ?Sized,
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T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
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T: ?Sized,
fn borrow_mut(&mut self) -> &mut T
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impl<T> From<T> for T
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impl<T, U> Into<U> for T where
U: From<T>,
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U: From<T>,
impl<T, U> TryFrom<U> for T where
U: Into<T>,
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U: Into<T>,
type Error = Infallible
The type returned in the event of a conversion error.
fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
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impl<T, U> TryInto<U> for T where
U: TryFrom<T>,
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U: TryFrom<T>,
type Error = <U as TryFrom<T>>::Error
The type returned in the event of a conversion error.
fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>
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impl<V, T> VZip<V> for T where
V: MultiLane<T>,
V: MultiLane<T>,