[arrow-datafusion] branch master updated: minor: add some comments to row group pruning tests (#4823)

[al...@apache.org]

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alamb pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/arrow-datafusion.git


The following commit(s) were added to refs/heads/master by this push:
     new 24023b5de minor: add some comments to row group pruning tests (#4823)
24023b5de is described below

commit 24023b5de7cc6c1223ce508d8686d70a8cc8110d
Author: Andrew Lamb <an...@nerdnetworks.org>
AuthorDate: Thu Jan 5 07:28:33 2023 -0500

    minor: add some comments to row group pruning tests (#4823)
---
 .../core/src/physical_plan/file_format/parquet/row_groups.rs       | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/datafusion/core/src/physical_plan/file_format/parquet/row_groups.rs b/datafusion/core/src/physical_plan/file_format/parquet/row_groups.rs
index 4aae795b4..101102c92 100644
--- a/datafusion/core/src/physical_plan/file_format/parquet/row_groups.rs
+++ b/datafusion/core/src/physical_plan/file_format/parquet/row_groups.rs
@@ -37,6 +37,13 @@ use crate::{
 
 use super::ParquetFileMetrics;
 
+/// Returns a vector of indexes into `groups` which should be scanned.
+///
+/// If an index is NOT present in the returned Vec it means the
+/// predicate filtered all the row group.
+///
+/// If an index IS present in the returned Vec it means the predicate
+/// did not filter out that row group.
 pub(crate) fn prune_row_groups(
     groups: &[RowGroupMetaData],
     range: Option<FileRange>,