Struct parquet::encoding::DictEncoder [−][src]
pub struct DictEncoder<T: DataType> { /* fields omitted */ }
Expand description
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
Creates new dictionary encoder.
Returns number of unique values (keys) in the dictionary.
Returns size of unique values (keys) in the dictionary, in bytes.
Writes out the dictionary values with PLAIN encoding in a byte buffer, and return the result.
Writes out the dictionary values with RLE encoding in a byte buffer, and return the result.
Trait Implementations
Auto Trait Implementations
impl<T> RefUnwindSafe for DictEncoder<T> where
<T as DataType>::T: RefUnwindSafe,
impl<T> Send for DictEncoder<T> where
<T as DataType>::T: Send,
impl<T> Sync for DictEncoder<T> where
<T as DataType>::T: Sync,
impl<T> Unpin for DictEncoder<T> where
<T as DataType>::T: Unpin,
impl<T> UnwindSafe for DictEncoder<T> where
<T as DataType>::T: UnwindSafe,