neverchanje opened a new issue #924: URL: https://github.com/apache/arrow-rs/issues/924
**Is your feature request related to a problem or challenge? Please describe what you are trying to do.** https://docs.rs/parquet/6.1.0/parquet/file/reader/trait.ChunkReader.html The `ChunkReader` trait is designed to hide the details of the underlying storage, which however may use the `async` feature, rusto-s3 for example: ```rust pub async fn get_object_range ``` https://durch.github.io/rust-s3/s3/bucket/struct.Bucket.html#method.get_object_range That means every `get_read` call has to be implemented by blocking on an async function. ```rust impl parquet::file::reader::ChunkReader for ParquetChunkReader { type T = SliceableCuror; fn get_read(&self, start: u64, length: usize) -> parquet::errors::Result<Self::SliceableCuror> { futures::executor::block_on(async move { bucket.get_object_range(...) }) } } ``` The non-async limitation of the ChunkReader trait will result in some problems, especially when the query execution engines are using async, tokio, e.g, it will have to use `tokio::spawn_blocking` to perform a parquet read. **Describe the solution you'd like** A clear and concise description of what you want to happen. We can add `async` to `ChunkReader::get_read`. ```rust #[async_trait::async_trait] pub trait ChunkReader: Length { type T: Read; async fn get_read(&self, start: u64, length: usize) -> Result<Self::T>; } ``` Many of the API will definitely need also to be changed to async. Until now I have no very clear idea and plan for moving them to the async version with backward compability. One possible solution is to provide a totally aync API, and the non-async API wraps it via `async_std::block_on`. ```rust pub trait RowGroupReaderAsync { async fn get_column_reader(&self, i: usize) -> Result<ColumnReader> { ... } } pub struct RowGroupReader { fn get_column_reader() { async_std::block_on(self.get_column_reader_async()) } } ``` **Describe alternatives you've considered** A clear and concise description of any alternative solutions or features you've considered. **Additional context** Add any other context or screenshots about the feature request here. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
