minor: fix to support scalars (#8559)

* minor: fix  to support scalars

* Update datafusion/sql/src/expr/function.rs

Co-authored-by: Andrew Lamb <andrew@nerdnetworks.org>

---------

Co-authored-by: Mustafa Akur <106137913+mustafasrepo@users.noreply.github.com>
Co-authored-by: Andrew Lamb <andrew@nerdnetworks.org>

Author: 3 people

datafusion/sql/src/expr/function.rs

@@ -90,6 +90,9 @@ impl<'a, S: ContextProvider> SqlToRel<'a, S> {
             let partition_by = window
                 .partition_by
                 .into_iter()
+                // ignore window spec PARTITION BY for scalar values
+                // as they do not change and thus do not generate new partitions
+                .filter(|e| !matches!(e, sqlparser::ast::Expr::Value { .. },))
                 .map(|e| self.sql_expr_to_logical_expr(e, schema, planner_context))
                 .collect::<Result<Vec<_>>>()?;
             let mut order_by = self.order_by_to_sort_expr(

datafusion/sqllogictest/test_files/window.slt

@@ -3794,8 +3794,36 @@ select a,
 1 1
 2 1
 
+# support scalar value in ORDER BY 
 query I
 select rank() over (order by 1) rnk from (select 1 a union all select 2 a) x
 ----
 1
 1
+
+# support scalar value in both ORDER BY and PARTITION BY, RANK function
+# TODO: fix the test, some issue in RANK
+#query IIIIII
+#select rank() over (partition by 1 order by 1) rnk,
+#       rank() over (partition by a, 1 order by 1) rnk1,
+#       rank() over (partition by a, 1 order by a, 1) rnk2,
+#       rank() over (partition by 1) rnk3,
+#       rank() over (partition by null) rnk4,
+#       rank() over (partition by 1, null, a) rnk5
+#from (select 1 a union all select 2 a) x
+#----
+#1 1 1 1 1 1
+#1 1 1 1 1 1
+
+# support scalar value in both ORDER BY and PARTITION BY, ROW_NUMBER function
+query IIIIII
+select row_number() over (partition by 1 order by 1) rn,
+       row_number() over (partition by a, 1 order by 1) rn1,
+       row_number() over (partition by a, 1 order by a, 1) rn2,
+       row_number() over (partition by 1) rn3,
+       row_number() over (partition by null) rn4,
+       row_number() over (partition by 1, null, a) rn5
+from (select 1 a union all select 2 a) x;
+----
+1 1 1 1 1 1
+2 1 1 2 2 1