Struct ReaderBuilder 

pub struct ReaderBuilder {
    schema: Option<SchemaRef>,
    batch_size: usize,
    projection: Option<Vec<String>>,
}

Avro file reader builder

Fields

schema: Option<SchemaRef>

Optional schema for the Avro file

If the schema is not supplied, the reader will try to read the schema.

batch_size: usize

Batch size (number of records to load each time)

The default batch size when using the ReaderBuilder is 1024 records

projection: Option<Vec<String>>

Optional projection for which columns to load (zero-based column indices)

Implementations

impl ReaderBuilder

pub fn new() -> Self

Create a new builder for configuring Avro parsing options.

To convert a builder into a reader, call Reader::from_builder

Example

use std::fs::File;

use datafusion_datasource_avro::avro_to_arrow::{Reader, ReaderBuilder};

fn example() -> Reader<'static, File> {
    let file = File::open("test/data/basic.avro").unwrap();

    // create a builder, inferring the schema with the first 100 records
    let builder = ReaderBuilder::new().read_schema().with_batch_size(100);

    let reader = builder.build::<File>(file).unwrap();

    reader
}

pub fn with_schema(self, schema: SchemaRef) -> Self

Set the Avro file’s schema

pub fn read_schema(self) -> Self

Set the Avro reader to infer the schema of the file

pub fn with_batch_size(self, batch_size: usize) -> Self

Set the batch size (number of records to load at one time)

pub fn with_projection(self, projection: Vec<String>) -> Self

Set the reader’s column projection

pub fn build<'a, R>(self, source: R) -> Result<Reader<'a, R>>

where R: Read + Seek,

Create a new Reader from the ReaderBuilder

Trait Implementations

impl Debug for ReaderBuilder

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

Formats the value using the given formatter.

impl Default for ReaderBuilder

fn default() -> Self

Returns the “default value” for a type.