Function parquet2::read::read_columns_async
source · pub async fn read_columns_async<'a, 'b, R: AsyncRead + AsyncSeek + Send + Unpin, F: Fn() -> BoxFuture<'b, Result<R>> + Clone>(
factory: F,
columns: &'a [ColumnChunkMetaData],
field_name: &'a str
) -> Result<Vec<(&'a ColumnChunkMetaData, Vec<u8>)>, Error>
Expand description
Reads all columns that are part of the parquet field field_name
§Implementation
This operation is IO-bounded O(C)
where C is the number of columns associated to
the field (one for non-nested types)
It does so asynchronously via a single join_all
over all the necessary columns for
field_name
.