diff --git a/parquet/src/arrow/async_reader/mod.rs b/parquet/src/arrow/async_reader/mod.rs index 5d5a7036eefb..413b2d68e6bc 100644 --- a/parquet/src/arrow/async_reader/mod.rs +++ b/parquet/src/arrow/async_reader/mod.rs @@ -98,10 +98,22 @@ pub trait AsyncFileReader: Send { .boxed() } - /// Provides asynchronous access to the [`ParquetMetaData`] of a parquet file, - /// allowing fine-grained control over how metadata is sourced, in particular allowing - /// for caching, pre-fetching, catalog metadata, etc... - /// ArrowReaderOptions may be provided to supply decryption parameters + /// Return a future which results in the [`ParquetMetaData`] for this Parquet file. + /// + /// This is an asynchronous operation as it may involve reading the file + /// footer and potentially other metadata from disk or a remote source. + /// + /// Reading data from Parquet requires the metadata to understand the + /// schema, row groups, and location of pages within the file. This metadata + /// is stored primarily in the footer of the Parquet file, and can be read using + /// [`ParquetMetaDataReader`]. + /// + /// However, implementations can significantly speed up reading Parquet by + /// supplying cached metadata or pre-fetched metadata via this API. + /// + /// # Parameters + /// * `options`: Optional [`ArrowReaderOptions`] that may contain decryption + /// and other options that affect how the metadata is read. fn get_metadata<'a>( &'a mut self, options: Option<&'a ArrowReaderOptions>,