Struct DictionaryTracker 

pub struct DictionaryTracker { /* private fields */ }

Keeps track of dictionaries that have been written, to avoid emitting the same dictionary multiple times.

Can optionally error if an update to an existing dictionary is attempted, which isn’t allowed in the FileWriter.

Implementations

impl DictionaryTracker

pub fn new(error_on_replacement: bool) -> DictionaryTracker

Create a new DictionaryTracker.

If error_on_replacement is true, an error will be generated if an update to an existing dictionary is attempted.

pub fn next_dict_id(&mut self) -> i64

Record and return the next dictionary ID.

pub fn dict_id(&mut self) -> &[i64]

Return the sequence of dictionary IDs in the order they should be observed while traversing the schema

pub fn insert( &mut self, dict_id: i64, column: &Arc<dyn Array>, ) -> Result<bool, ArrowError>

👎Deprecated since 56.1.0: Use insert_column instead

Keep track of the dictionary with the given ID and values. Behavior:

• If this ID has been written already and has the same data, return Ok(false) to indicate that the dictionary was not actually inserted (because it’s already been seen).
• If this ID has been written already but with different data, and this tracker is configured to return an error, return an error.
• If the tracker has not been configured to error on replacement or this dictionary has never been seen before, return Ok(true) to indicate that the dictionary was just inserted.

pub fn insert_column( &mut self, dict_id: i64, column: &Arc<dyn Array>, dict_handling: DictionaryHandling, ) -> Result<DictionaryUpdate, ArrowError>

Keep track of the dictionary with the given ID and values. The return value indicates what, if any, update to the internal map took place and how it should be interpreted based on the dict_handling parameter.

Returns

• Ok(Dictionary::New) - If the dictionary was not previously written
• Ok(Dictionary::Replaced) - If the dictionary was previously written with completely different data, or if the data is a delta of the existing, but with dict_handling set to DictionaryHandling::Resend
• Ok(Dictionary::Delta) - If the dictionary was previously written, but the new data is a delta of the old and the dict_handling is set to DictionaryHandling::Delta
• Err(e) - If the dictionary was previously written with different data, and error_on_replacement is set to true.

Trait Implementations

impl Debug for DictionaryTracker

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.