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datafusion/sqllogictest/test_files/monotonic_projection_test.slt

@@ -65,7 +65,11 @@ SortPreservingMergeExec: [a@0 ASC NULLS LAST,b@2 ASC NULLS LAST]
 ----RepartitionExec: partitioning=RoundRobinBatch(4), input_partitions=1
 ------CsvExec: file_groups={1 group: [[WORKSPACE_ROOT/datafusion/core/tests/data/window_2.csv]]}, projection=[a, b], output_ordering=[a@0 ASC NULLS LAST, b@1 ASC NULLS LAST], has_header=true
 
-# TODO: Should generate without SortExec
+// Cast to larger types as well as preserving ordering
+// doesn't invalidate lexicographical ordering.
+// Hence '[CAST(a AS BIGINT) AS a_big ASC, b ASC]'
+// is valid for the given ordering: '[a ASC, b ASC]'.
+// See discussion for rationale: https://github.com/apache/arrow-datafusion/issues/8838#issue-2077714891
 query TT
 EXPLAIN
 SELECT a, CAST(a AS BIGINT) AS a_big, b