rdettai commented on a change in pull request #2000:
URL: https://github.com/apache/arrow-datafusion/pull/2000#discussion_r834021207
##########
File path: datafusion/src/physical_plan/file_format/parquet.rs
##########
@@ -435,6 +448,56 @@ fn build_row_group_predicate(
)
}
+fn read_partition_no_file_columns(
+ object_store: &dyn ObjectStore,
+ partition: &[PartitionedFile],
+ batch_size: usize,
+ response_tx: Sender<ArrowResult<RecordBatch>>,
+ mut limit: Option<usize>,
+ mut partition_column_projector: PartitionColumnProjector,
+) -> Result<()> {
+ use parquet::file::reader::FileReader;
+ for partitioned_file in partition {
+ let object_reader =
+
object_store.file_reader(partitioned_file.file_meta.sized_file.clone())?;
+ let file_reader =
SerializedFileReader::new(ChunkObjectReader(object_reader))?;
+ let mut file_rows: usize = file_reader
+ .metadata()
+ .file_metadata()
+ .num_rows()
+ .try_into()
+ .expect("Row count should always be greater than or equal to 0");
+ let remaining_rows = limit.unwrap_or(usize::MAX);
+ if file_rows >= remaining_rows {
+ file_rows = remaining_rows;
+ limit = Some(0);
+ } else if let Some(remaining_limit) = &mut limit {
+ *remaining_limit -= file_rows;
+ }
Review comment:
Unwrapping the limit `Option` outside the loop would avoid having to
mutate limit and decrease complexity a bit more.
##########
File path: datafusion/src/physical_plan/file_format/mod.rs
##########
@@ -293,6 +293,36 @@ impl PartitionColumnProjector {
}
}
+ // Creates a RecordBatch with values from the partition_values. Used when
no non-partition values are read
+ fn project_empty(
Review comment:
what about `project_from_size` instead?
##########
File path: datafusion/src/physical_plan/file_format/parquet.rs
##########
@@ -435,6 +448,56 @@ fn build_row_group_predicate(
)
}
+fn read_partition_no_file_columns(
+ object_store: &dyn ObjectStore,
+ partition: &[PartitionedFile],
+ batch_size: usize,
+ response_tx: Sender<ArrowResult<RecordBatch>>,
+ mut limit: Option<usize>,
+ mut partition_column_projector: PartitionColumnProjector,
+) -> Result<()> {
+ use parquet::file::reader::FileReader;
+ for partitioned_file in partition {
+ let object_reader =
+
object_store.file_reader(partitioned_file.file_meta.sized_file.clone())?;
+ let file_reader =
SerializedFileReader::new(ChunkObjectReader(object_reader))?;
+ let mut file_rows: usize = file_reader
+ .metadata()
+ .file_metadata()
+ .num_rows()
+ .try_into()
+ .expect("Row count should always be greater than or equal to 0");
+ let remaining_rows = limit.unwrap_or(usize::MAX);
+ if file_rows >= remaining_rows {
+ file_rows = remaining_rows;
+ limit = Some(0);
+ } else if let Some(remaining_limit) = &mut limit {
+ *remaining_limit -= file_rows;
+ }
+
+ while file_rows > batch_size {
+ send_result(
+ &response_tx,
+ partition_column_projector
+ .project_empty(batch_size,
&partitioned_file.partition_values),
+ )?;
+ file_rows -= batch_size;
+ }
+ if file_rows != 0 {
+ send_result(
+ &response_tx,
+ partition_column_projector
+ .project_empty(batch_size,
&partitioned_file.partition_values),
+ )?;
+ }
+
+ if limit == Some(0) {
+ break;
+ }
+ }
+ Ok(())
+}
Review comment:
I still feel this could be simplified and made more readable by using
more iterators:
- iterate over file
- map them to their size
- map each size to an iterator that repeats the batch size
file_rows/batch_size times + residual
- flat map the whole thing
- apply limit with `take(limit)`
- for_each(send)
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