From ec449104d7ca6fe9b843fdc03e8338ecb768af3c Mon Sep 17 00:00:00 2001
From: Jay Miller <3744812+jaylmiller@users.noreply.github.com>
Date: Fri, 10 Feb 2023 11:56:26 -0500
Subject: [PATCH] modify sort_batch to use arrow row format for multi-column
 sorts

---
 .../core/src/physical_plan/sorts/sort.rs      | 27 +++++++++++++++++--
 1 file changed, 25 insertions(+), 2 deletions(-)

diff --git a/datafusion/core/src/physical_plan/sorts/sort.rs b/datafusion/core/src/physical_plan/sorts/sort.rs
index ad08504c3b86..286bfab02d12 100644
--- a/datafusion/core/src/physical_plan/sorts/sort.rs
+++ b/datafusion/core/src/physical_plan/sorts/sort.rs
@@ -38,13 +38,14 @@ use crate::physical_plan::{
     RecordBatchStream, SendableRecordBatchStream, Statistics,
 };
 use crate::prelude::SessionConfig;
-use arrow::array::{make_array, Array, ArrayRef, MutableArrayData};
+use arrow::array::{make_array, Array, ArrayRef, MutableArrayData, UInt32Array};
 pub use arrow::compute::SortOptions;
 use arrow::compute::{concat, lexsort_to_indices, take, SortColumn, TakeOptions};
 use arrow::datatypes::SchemaRef;
 use arrow::error::ArrowError;
 use arrow::ipc::reader::FileReader;
 use arrow::record_batch::RecordBatch;
+use arrow::row::{Row, RowConverter, SortField};
 use datafusion_physical_expr::EquivalenceProperties;
 use futures::{Stream, StreamExt, TryStreamExt};
 use log::{debug, error};
@@ -820,7 +821,29 @@ fn sort_batch(
         .map(|e| e.evaluate_to_sort_column(&batch))
         .collect::<Result<Vec<SortColumn>>>()?;
 
-    let indices = lexsort_to_indices(&sort_columns, fetch)?;
+    let indices = if sort_columns.len() == 1 {
+        lexsort_to_indices(&sort_columns, fetch)?
+    } else {
+        let sort_fields = sort_columns
+            .iter()
+            .map(|c| {
+                let datatype = c.values.data_type().to_owned();
+                SortField::new_with_options(datatype, c.options.unwrap_or_default())
+            })
+            .collect::<Vec<_>>();
+        let arrays: Vec<ArrayRef> =
+            sort_columns.iter().map(|c| c.values.clone()).collect();
+        let mut row_converter = RowConverter::new(sort_fields)?;
+        let rows = row_converter.convert_columns(&arrays)?;
+
+        let mut to_sort: Vec<(usize, Row)> = rows.into_iter().enumerate().collect();
+        to_sort.sort_unstable_by(|(_, row_a), (_, row_b)| row_a.cmp(row_b));
+        let limit = match fetch {
+            Some(lim) => lim.min(to_sort.len()),
+            None => to_sort.len(),
+        };
+        UInt32Array::from_iter(to_sort.into_iter().take(limit).map(|(idx, _)| idx as u32))
+    };
 
     // reorder all rows based on sorted indices
     let sorted_batch = RecordBatch::try_new(