Struct ReaderFactory 

pub struct ReaderFactory { /* private fields */ }

A custom [ParquetFileReaderFactory] that handles opening parquet files from object storage, and loads metadata on-demand.

Parsed metadata is cached globally across all readers and queries via a shared MetadataCache, significantly reducing repeated object-storage footer reads for repeated queries on the same partitions.

File content caching is the responsibility of object_store itself: this factory is typically constructed with an object store already wrapped by the in-process L1 cache (see object_cache::l1_wrap), so it just reads bytes through it directly.

Implementations

impl ReaderFactory

pub fn new( object_store: Arc<dyn ObjectStore>, metadata_cache: Arc<MetadataCache>, ) -> ReaderFactory

Creates a new ReaderFactory with a shared metadata cache, reading file contents through object_store.

Trait Implementations

impl Debug for ReaderFactory

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

Formats the value using the given formatter.

impl ParquetFileReaderFactory for ReaderFactory

fn create_reader( &self, partition_index: usize, partitioned_file: PartitionedFile, _metadata_size_hint: Option<usize>, metrics: &ExecutionPlanMetricsSet, ) -> Result<Box<dyn AsyncFileReader + Send>, DataFusionError>

Provides an AsyncFileReader for reading data from a parquet file specified