Trait IndexReader

pub trait IndexReader: Send + Sync {
    // Required methods
    fn read_record_batch<'life0, 'async_trait>(
        &'life0 self,
        n: u32,
    ) -> Pin<Box<dyn Future<Output = Result<RecordBatch>> + Send + 'async_trait>>
       where Self: 'async_trait,
             'life0: 'async_trait;
    fn read_range<'life0, 'life1, 'life2, 'async_trait>(
        &'life0 self,
        range: Range<usize>,
        projection: Option<&'life1 [&'life2 str]>,
    ) -> Pin<Box<dyn Future<Output = Result<RecordBatch>> + Send + 'async_trait>>
       where Self: 'async_trait,
             'life0: 'async_trait,
             'life1: 'async_trait,
             'life2: 'async_trait;
    fn num_batches<'life0, 'async_trait>(
        &'life0 self,
    ) -> Pin<Box<dyn Future<Output = u32> + Send + 'async_trait>>
       where Self: 'async_trait,
             'life0: 'async_trait;
    fn num_rows(&self) -> usize;
    fn schema(&self) -> &Schema;
}

Trait for reading an index (or parts of an index) from storage

Required Methods

fn read_record_batch<'life0, 'async_trait>( &'life0 self, n: u32, ) -> Pin<Box<dyn Future<Output = Result<RecordBatch>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Read the n-th record batch from the file

fn read_range<'life0, 'life1, 'life2, 'async_trait>( &'life0 self, range: Range<usize>, projection: Option<&'life1 [&'life2 str]>, ) -> Pin<Box<dyn Future<Output = Result<RecordBatch>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait, 'life2: 'async_trait,

Read the range of rows from the file. If projection is Some, only return the columns in the projection, nested columns like Some(&[“x.y”]) are not supported. If projection is None, return all columns.

fn num_batches<'life0, 'async_trait>( &'life0 self, ) -> Pin<Box<dyn Future<Output = u32> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Return the number of batches in the file

fn num_rows(&self) -> usize

Return the number of rows in the file

fn schema(&self) -> &Schema

Return the metadata of the file

Implementations on Foreign Types

impl IndexReader for FileReader

fn read_record_batch<'life0, 'async_trait>( &'life0 self, offset: u32, ) -> Pin<Box<dyn Future<Output = Result<RecordBatch>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

fn read_range<'life0, 'life1, 'life2, 'async_trait>( &'life0 self, range: Range<usize>, projection: Option<&'life1 [&'life2 str]>, ) -> Pin<Box<dyn Future<Output = Result<RecordBatch>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait, 'life2: 'async_trait,

fn num_batches<'life0, 'async_trait>( &'life0 self, ) -> Pin<Box<dyn Future<Output = u32> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

fn num_rows(&self) -> usize

fn schema(&self) -> &Schema

impl IndexReader for FileReader

fn read_record_batch<'life0, 'async_trait>( &'life0 self, _offset: u32, ) -> Pin<Box<dyn Future<Output = Result<RecordBatch>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

fn read_range<'life0, 'life1, 'life2, 'async_trait>( &'life0 self, range: Range<usize>, projection: Option<&'life1 [&'life2 str]>, ) -> Pin<Box<dyn Future<Output = Result<RecordBatch>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait, 'life2: 'async_trait,

fn num_batches<'life0, 'async_trait>( &'life0 self, ) -> Pin<Box<dyn Future<Output = u32> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

fn num_rows(&self) -> usize

fn schema(&self) -> &Schema

Implementors