[GitHub] [arrow-datafusion] Cheappie commented on a diff in pull request #2170: Handle merged schemas in parquet pruning

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

Cheappie commented on code in PR #2170:
URL: https://github.com/apache/arrow-datafusion/pull/2170#discussion_r845538137


##########
datafusion/core/src/physical_plan/file_format/parquet.rs:
##########
@@ -919,6 +955,73 @@ mod tests {
         assert_batches_sorted_eq!(expected, &read);
     }
 
+    #[tokio::test]
+    async fn evolved_schema_filter() {
+        let c1: ArrayRef =
+            Arc::new(StringArray::from(vec![Some("Foo"), None, Some("bar")]));
+
+        let c2: ArrayRef = Arc::new(Int64Array::from(vec![Some(1), Some(2), None]));
+
+        let c3: ArrayRef = Arc::new(Int8Array::from(vec![Some(10), Some(20), None]));
+
+        // batch1: c1(string), c2(int64), c3(int8)
+        let batch1 = create_batch(vec![
+            ("c1", c1.clone()),
+            ("c2", c2.clone()),
+            ("c3", c3.clone()),
+        ]);
+
+        // batch2: c3(int8), c2(int64), c1(string)
+        let batch2 = create_batch(vec![("c3", c3), ("c2", c2), ("c1", c1)]);
+
+        let filter = col("c3").eq(lit(0_i8));
+
+        // read/write them files:
+        let read = round_trip_to_parquet(vec![batch1, batch2], None, None, Some(filter))
+            .await
+            .unwrap();
+
+        // Predicate should prune all row groups
+        assert_eq!(read.len(), 0);
+    }
+
+    #[tokio::test]
+    async fn evolved_schema_disjoint_schema_filter() {
+        let c1: ArrayRef =
+            Arc::new(StringArray::from(vec![Some("Foo"), None, Some("bar")]));
+
+        let c2: ArrayRef = Arc::new(Int64Array::from(vec![Some(1), Some(2), None]));

Review Comment:
   I might miss some point, but why values in c2 are not materialized if we weren't able to _prune_ them ? I wonder how filter like `c2 eq 1_i64` can be satisfied against null array ?
   
   ```
               "+-----+----+",
               "| c1  | c2 |",
               "+-----+----+",
               "| Foo |    |",
               "|     |    |",
               "| bar |    |",
               "+-----+----+",
   ```



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