Fix indented display for multi-child nodes (#358)

Author: alamb

datafusion/src/physical_plan/display.rs

@@ -87,4 +87,9 @@ impl<'a, 'b> ExecutionPlanVisitor for IndentVisitor<'a, 'b> {
         self.indent += 1;
         Ok(true)
     }
+
+    fn post_visit(&mut self, _plan: &dyn ExecutionPlan) -> Result<bool, Self::Error> {
+        self.indent -= 1;
+        Ok(true)
+    }
 }

datafusion/tests/sql.rs

@@ -2989,3 +2989,52 @@ async fn test_physical_plan_display_indent() {
         expected, actual
     );
 }
+
+#[tokio::test]
+async fn test_physical_plan_display_indent_multi_children() {
+    // Hard code concurrency as it appears in the RepartitionExec output
+    let config = ExecutionConfig::new().with_concurrency(3);
+    let mut ctx = ExecutionContext::with_config(config);
+    // ensure indenting works for nodes with multiple children
+    register_aggregate_csv(&mut ctx).unwrap();
+    let sql = "SELECT c1 \
+               FROM (select c1 from aggregate_test_100)\
+                 JOIN\
+                    (select c1 as c2 from aggregate_test_100)\
+                 ON c1=c2\
+                 ";
+
+    let plan = ctx.create_logical_plan(&sql).unwrap();
+    let plan = ctx.optimize(&plan).unwrap();
+
+    let physical_plan = ctx.create_physical_plan(&plan).unwrap();
+    let expected = vec![
+        "ProjectionExec: expr=[c1]",
+        "  CoalesceBatchesExec: target_batch_size=4096",
+        "    HashJoinExec: mode=Partitioned, join_type=Inner, on=[(\"c1\", \"c2\")]",
+        "      CoalesceBatchesExec: target_batch_size=4096",
+        "        RepartitionExec: partitioning=Hash([Column { name: \"c1\" }], 3)",
+        "          ProjectionExec: expr=[c1]",
+        "            RepartitionExec: partitioning=RoundRobinBatch(3)",
+        "              CsvExec: source=Path(ARROW_TEST_DATA/csv/aggregate_test_100.csv: [ARROW_TEST_DATA/csv/aggregate_test_100.csv]), has_header=true",
+        "      CoalesceBatchesExec: target_batch_size=4096",
+        "        RepartitionExec: partitioning=Hash([Column { name: \"c2\" }], 3)",
+        "          ProjectionExec: expr=[c1 as c2]",
+        "            RepartitionExec: partitioning=RoundRobinBatch(3)",
+        "              CsvExec: source=Path(ARROW_TEST_DATA/csv/aggregate_test_100.csv: [ARROW_TEST_DATA/csv/aggregate_test_100.csv]), has_header=true",
+    ];
+
+    let data_path = arrow::util::test_util::arrow_test_data();
+    let actual = format!("{}", displayable(physical_plan.as_ref()).indent())
+        .trim()
+        .lines()
+        // normalize paths
+        .map(|s| s.replace(&data_path, "ARROW_TEST_DATA"))
+        .collect::<Vec<_>>();
+
+    assert_eq!(
+        expected, actual,
+        "expected:\n{:#?}\nactual:\n\n{:#?}\n",
+        expected, actual
+    );
+}