Function arrow2::io::parquet::read::read_columns_many_async

pub async fn read_columns_many_async<'a, 'b, R: AsyncRead + AsyncSeek + Send + Unpin, F: Fn() -> BoxFuture<'b, Result<R>> + Clone>(
    reader_factory: F,
    row_group: &RowGroupMetaData,
    fields: Vec<Field>,
    chunk_size: Option<usize>,
    limit: Option<usize>,
    pages: Option<Vec<Vec<Vec<FilteredPage>>>>
) -> Result<Vec<ArrayIter<'a>>>

Returns a vector of iterators of Array corresponding to the top level parquet fields whose name matches fields’s names.

Implementation

This operation is IO-bounded O(C) where C is the number of columns in the row group - it reads all the columns to memory from the row group associated to the requested fields. It does so asynchronously via join_all