[GitHub] [arrow-datafusion] Jimexist commented on a change in pull request #558: Implement window functions with `partition_by` clause

[GitBox <gi...@apache.org>]

Jimexist commented on a change in pull request #558:
URL: https://github.com/apache/arrow-datafusion/pull/558#discussion_r654755492



##########
File path: datafusion/src/execution/context.rs
##########
@@ -1352,6 +1352,90 @@ mod tests {
         Ok(())
     }
 
+    #[tokio::test]
+    async fn window_partition_by() -> Result<()> {
+        let results = execute(
+            "SELECT \
+            c1, \
+            c2, \
+            SUM(c2) OVER (PARTITION BY c2), \
+            COUNT(c2) OVER (PARTITION BY c2), \
+            MAX(c2) OVER (PARTITION BY c2), \
+            MIN(c2) OVER (PARTITION BY c2), \
+            AVG(c2) OVER (PARTITION BY c2) \
+            FROM test \
+            ORDER BY c1, c2 \
+            LIMIT 5",
+            4,
+        )
+        .await?;
+        dbg!(results.len());
+        // result in one batch, although e.g. having 2 batches do not change
+        // result semantics, having a len=1 assertion upfront keeps surprises
+        // at bay
+        assert_eq!(results.len(), 1);
+
+        let expected = vec![
+            "+----+----+---------+-----------+---------+---------+---------+",
+            "| c1 | c2 | SUM(c2) | COUNT(c2) | MAX(c2) | MIN(c2) | AVG(c2) |",
+            "+----+----+---------+-----------+---------+---------+---------+",
+            "| 0  | 1  | 4       | 4         | 1       | 1       | 1       |",
+            "| 0  | 2  | 8       | 4         | 2       | 2       | 2       |",
+            "| 0  | 3  | 12      | 4         | 3       | 3       | 3       |",
+            "| 0  | 4  | 16      | 4         | 4       | 4       | 4       |",
+            "| 0  | 5  | 20      | 4         | 5       | 5       | 5       |",
+            "+----+----+---------+-----------+---------+---------+---------+",
+        ];
+
+        // window function shall respect ordering
+        assert_batches_eq!(expected, &results);
+        Ok(())
+    }
+
+    #[tokio::test]
+    async fn window_partition_by_order_by() -> Result<()> {
+        let results = execute(
+            "SELECT \
+            c1, \
+            c2, \
+            ROW_NUMBER() OVER (PARTITION BY c2 ORDER BY c1), \
+            FIRST_VALUE(c2) OVER (PARTITION BY c2 ORDER BY c1), \
+            LAST_VALUE(c2) OVER (PARTITION BY c2 ORDER BY c1), \
+            NTH_VALUE(c2, 2) OVER (PARTITION BY c2 ORDER BY c1), \
+            SUM(c2) OVER (PARTITION BY c2 ORDER BY c1), \
+            COUNT(c2) OVER (PARTITION BY c2 ORDER BY c1), \
+            MAX(c2) OVER (PARTITION BY c2 ORDER BY c1), \
+            MIN(c2) OVER (PARTITION BY c2 ORDER BY c1), \
+            AVG(c2) OVER (PARTITION BY c2 ORDER BY c1) \
+            FROM test \
+            ORDER BY c1, c2 \
+            LIMIT 5",
+            4,
+        )
+        .await?;
+        dbg!(results.len());
+        // result in one batch, although e.g. having 2 batches do not change
+        // result semantics, having a len=1 assertion upfront keeps surprises
+        // at bay
+        assert_eq!(results.len(), 1);
+
+        let expected = vec![
+            "+----+----+--------------+-----------------+----------------+------------------------+---------+-----------+---------+---------+---------+",
+            "| c1 | c2 | ROW_NUMBER() | FIRST_VALUE(c2) | LAST_VALUE(c2) | NTH_VALUE(c2,Int64(2)) | SUM(c2) | COUNT(c2) | MAX(c2) | MIN(c2) | AVG(c2) |",
+            "+----+----+--------------+-----------------+----------------+------------------------+---------+-----------+---------+---------+---------+",

Review comment:
       i updated the function parameters so now they are different




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