[ASTERIXDB-3409][COMP] Ensure no modifications on irreplaceable root

- user model changes: no
- storage format changes: no
- interface changes: no

Details:
Implement missing allowsReplacing() in RootExpectedSchemaNode

Change-Id: I46ca394a976265d9ae6be73ec2236e8d7f056b29
Reviewed-on: https://asterix-gerrit.ics.uci.edu/c/asterixdb/+/18329
Integration-Tests: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Tested-by: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Reviewed-by: Wail Alkowaileet <wael.y.k@gmail.com>
Reviewed-by: Peeyush Gupta <peeyush.gupta@couchbase.com>
diff --git a/asterixdb/asterix-algebra/src/main/java/org/apache/asterix/optimizer/rules/pushdown/schema/RootExpectedSchemaNode.java b/asterixdb/asterix-algebra/src/main/java/org/apache/asterix/optimizer/rules/pushdown/schema/RootExpectedSchemaNode.java
index 672de68..72c5c52 100644
--- a/asterixdb/asterix-algebra/src/main/java/org/apache/asterix/optimizer/rules/pushdown/schema/RootExpectedSchemaNode.java
+++ b/asterixdb/asterix-algebra/src/main/java/org/apache/asterix/optimizer/rules/pushdown/schema/RootExpectedSchemaNode.java
@@ -45,6 +45,11 @@
     }
 
     @Override
+    public boolean allowsReplacing() {
+        return rootType != ALL_FIELDS_ROOT_IRREPLACEABLE;
+    }
+
+    @Override
     public boolean isRoot() {
         return true;
     }
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/column/pushdown/other-pushdowns/other-pushdowns.020.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/column/pushdown/other-pushdowns/other-pushdowns.020.query.sqlpp
new file mode 100644
index 0000000..784b004
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/column/pushdown/other-pushdowns/other-pushdowns.020.query.sqlpp
@@ -0,0 +1,31 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+-- This query and the next one are related (see ASTERIXDB-3409)
+USE test;
+SET `compiler.parallelism` "0";
+SET `compiler.sort.parallel` "false";
+EXPLAIN
+SELECT COUNT(DISTINCT R3.id) AS count
+FROM (
+SELECT t.*
+FROM ColumnDataset AS t
+WHERE ((ARRAY_SUM((
+        SELECT VALUE i.`count`
+        FROM t.`a1` AS i)) >= 3 ))) AS R3
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/column/pushdown/other-pushdowns/other-pushdowns.021.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/column/pushdown/other-pushdowns/other-pushdowns.021.query.sqlpp
new file mode 100644
index 0000000..ab3a4c5
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/column/pushdown/other-pushdowns/other-pushdowns.021.query.sqlpp
@@ -0,0 +1,31 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+-- This query and the previous one are related (see ASTERIXDB-3409)
+USE test;
+SET `compiler.parallelism` "0";
+SET `compiler.sort.parallel` "false";
+EXPLAIN
+SELECT COUNT(DISTINCT R3.id) AS count
+FROM (
+SELECT t.*
+FROM ColumnDataset AS t
+WHERE ((ARRAY_SUM((
+        SELECT VALUE i.`count`
+        FROM t.`a1` AS i)) >= 3 ))) AS R3
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/column/pushdown/other-pushdowns/other-pushdowns.020.plan b/asterixdb/asterix-app/src/test/resources/runtimets/results/column/pushdown/other-pushdowns/other-pushdowns.020.plan
new file mode 100644
index 0000000..e370904
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/column/pushdown/other-pushdowns/other-pushdowns.020.plan
@@ -0,0 +1,51 @@
+distribute result [$$68] [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+-- DISTRIBUTE_RESULT  |UNPARTITIONED|
+  exchange [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+  -- ONE_TO_ONE_EXCHANGE  |UNPARTITIONED|
+    project ([$$68]) [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+    -- STREAM_PROJECT  |UNPARTITIONED|
+      assign [$$68] <- [{"count": $$71}] [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+      -- ASSIGN  |UNPARTITIONED|
+        aggregate [$$71] <- [agg-sql-count(1)] [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+        -- AGGREGATE  |UNPARTITIONED|
+          exchange [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+          -- SORT_MERGE_EXCHANGE [$$66(ASC) ]  |PARTITIONED|
+            distinct ([$$66]) [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+            -- PRE_SORTED_DISTINCT_BY  |PARTITIONED|
+              exchange [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+              -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                order (ASC, $$66) [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                -- STABLE_SORT [$$66(ASC)]  |PARTITIONED|
+                  exchange [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                  -- HASH_PARTITION_EXCHANGE [$$66]  |PARTITIONED|
+                    project ([$$66]) [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                    -- STREAM_PROJECT  |PARTITIONED|
+                      select (ge($$70, 3)) [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                      -- STREAM_SELECT  |PARTITIONED|
+                        project ([$$66, $$70]) [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                        -- STREAM_PROJECT  |PARTITIONED|
+                          subplan {
+                                    aggregate [$$70] <- [agg-sql-sum($$52)] [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                                    -- AGGREGATE  |LOCAL|
+                                      assign [$$52] <- [$$i.getField("count")] [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                                      -- ASSIGN  |LOCAL|
+                                        unnest $$i <- scan-collection($$72) [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                                        -- UNNEST  |LOCAL|
+                                          nested tuple source [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                                          -- NESTED_TUPLE_SOURCE  |LOCAL|
+                                 } [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                          -- SUBPLAN  |PARTITIONED|
+                            project ([$$66, $$72]) [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                            -- STREAM_PROJECT  |PARTITIONED|
+                              assign [$$66, $$72] <- [if-missing-or-null(to-object($$t), cast({  })).getField(0), $$t.getField("a1")] [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                              -- ASSIGN  |PARTITIONED|
+                                project ([$$t]) [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                                -- STREAM_PROJECT  |PARTITIONED|
+                                  exchange [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                                  -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                    data-scan []<-[$$69, $$t] <- test.ColumnDataset [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                                    -- DATASOURCE_SCAN  |PARTITIONED|
+                                      exchange [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                                      -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                        empty-tuple-source [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                                        -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/column/pushdown/other-pushdowns/other-pushdowns.021.plan b/asterixdb/asterix-app/src/test/resources/runtimets/results/column/pushdown/other-pushdowns/other-pushdowns.021.plan
new file mode 100644
index 0000000..e370904
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/column/pushdown/other-pushdowns/other-pushdowns.021.plan
@@ -0,0 +1,51 @@
+distribute result [$$68] [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+-- DISTRIBUTE_RESULT  |UNPARTITIONED|
+  exchange [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+  -- ONE_TO_ONE_EXCHANGE  |UNPARTITIONED|
+    project ([$$68]) [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+    -- STREAM_PROJECT  |UNPARTITIONED|
+      assign [$$68] <- [{"count": $$71}] [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+      -- ASSIGN  |UNPARTITIONED|
+        aggregate [$$71] <- [agg-sql-count(1)] [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+        -- AGGREGATE  |UNPARTITIONED|
+          exchange [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+          -- SORT_MERGE_EXCHANGE [$$66(ASC) ]  |PARTITIONED|
+            distinct ([$$66]) [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+            -- PRE_SORTED_DISTINCT_BY  |PARTITIONED|
+              exchange [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+              -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                order (ASC, $$66) [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                -- STABLE_SORT [$$66(ASC)]  |PARTITIONED|
+                  exchange [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                  -- HASH_PARTITION_EXCHANGE [$$66]  |PARTITIONED|
+                    project ([$$66]) [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                    -- STREAM_PROJECT  |PARTITIONED|
+                      select (ge($$70, 3)) [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                      -- STREAM_SELECT  |PARTITIONED|
+                        project ([$$66, $$70]) [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                        -- STREAM_PROJECT  |PARTITIONED|
+                          subplan {
+                                    aggregate [$$70] <- [agg-sql-sum($$52)] [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                                    -- AGGREGATE  |LOCAL|
+                                      assign [$$52] <- [$$i.getField("count")] [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                                      -- ASSIGN  |LOCAL|
+                                        unnest $$i <- scan-collection($$72) [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                                        -- UNNEST  |LOCAL|
+                                          nested tuple source [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                                          -- NESTED_TUPLE_SOURCE  |LOCAL|
+                                 } [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                          -- SUBPLAN  |PARTITIONED|
+                            project ([$$66, $$72]) [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                            -- STREAM_PROJECT  |PARTITIONED|
+                              assign [$$66, $$72] <- [if-missing-or-null(to-object($$t), cast({  })).getField(0), $$t.getField("a1")] [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                              -- ASSIGN  |PARTITIONED|
+                                project ([$$t]) [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                                -- STREAM_PROJECT  |PARTITIONED|
+                                  exchange [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                                  -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                    data-scan []<-[$$69, $$t] <- test.ColumnDataset [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                                    -- DATASOURCE_SCAN  |PARTITIONED|
+                                      exchange [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                                      -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                        empty-tuple-source [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                                        -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results_cbo/column/pushdown/other-pushdowns/other-pushdowns.020.plan b/asterixdb/asterix-app/src/test/resources/runtimets/results_cbo/column/pushdown/other-pushdowns/other-pushdowns.020.plan
new file mode 100644
index 0000000..4e264fa
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results_cbo/column/pushdown/other-pushdowns/other-pushdowns.020.plan
@@ -0,0 +1,51 @@
+distribute result [$$68] [cardinality: 0.0, op-cost: 0.0, total-cost: 2.0]
+-- DISTRIBUTE_RESULT  |UNPARTITIONED|
+  exchange [cardinality: 0.0, op-cost: 0.0, total-cost: 2.0]
+  -- ONE_TO_ONE_EXCHANGE  |UNPARTITIONED|
+    project ([$$68]) [cardinality: 0.0, op-cost: 0.0, total-cost: 2.0]
+    -- STREAM_PROJECT  |UNPARTITIONED|
+      assign [$$68] <- [{"count": $$71}] [cardinality: 0.0, op-cost: 0.0, total-cost: 2.0]
+      -- ASSIGN  |UNPARTITIONED|
+        aggregate [$$71] <- [agg-sql-count(1)] [cardinality: 0.0, op-cost: 0.0, total-cost: 2.0]
+        -- AGGREGATE  |UNPARTITIONED|
+          exchange [cardinality: 0.0, op-cost: 0.0, total-cost: 2.0]
+          -- SORT_MERGE_EXCHANGE [$$66(ASC) ]  |PARTITIONED|
+            distinct ([$$66]) [cardinality: 0.0, op-cost: 0.0, total-cost: 2.0]
+            -- PRE_SORTED_DISTINCT_BY  |PARTITIONED|
+              exchange [cardinality: 0.0, op-cost: 0.0, total-cost: 2.0]
+              -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                order (ASC, $$66) [cardinality: 0.0, op-cost: 0.0, total-cost: 2.0]
+                -- STABLE_SORT [$$66(ASC)]  |PARTITIONED|
+                  exchange [cardinality: 0.0, op-cost: 0.0, total-cost: 2.0]
+                  -- HASH_PARTITION_EXCHANGE [$$66]  |PARTITIONED|
+                    project ([$$66]) [cardinality: 0.0, op-cost: 0.0, total-cost: 2.0]
+                    -- STREAM_PROJECT  |PARTITIONED|
+                      select (ge($$70, 3)) [cardinality: 0.0, op-cost: 0.0, total-cost: 2.0]
+                      -- STREAM_SELECT  |PARTITIONED|
+                        project ([$$66, $$70]) [cardinality: 2.0, op-cost: 0.0, total-cost: 2.0]
+                        -- STREAM_PROJECT  |PARTITIONED|
+                          subplan {
+                                    aggregate [$$70] <- [agg-sql-sum($$52)] [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                                    -- AGGREGATE  |LOCAL|
+                                      assign [$$52] <- [$$i.getField("count")] [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                                      -- ASSIGN  |LOCAL|
+                                        unnest $$i <- scan-collection($$72) [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                                        -- UNNEST  |LOCAL|
+                                          nested tuple source [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                                          -- NESTED_TUPLE_SOURCE  |LOCAL|
+                                 } [cardinality: 2.0, op-cost: 0.0, total-cost: 2.0]
+                          -- SUBPLAN  |PARTITIONED|
+                            project ([$$66, $$72]) [cardinality: 2.0, op-cost: 0.0, total-cost: 2.0]
+                            -- STREAM_PROJECT  |PARTITIONED|
+                              assign [$$66, $$72] <- [if-missing-or-null(to-object($$t), cast({  })).getField(0), $$t.getField("a1")] [cardinality: 2.0, op-cost: 0.0, total-cost: 2.0]
+                              -- ASSIGN  |PARTITIONED|
+                                project ([$$t]) [cardinality: 2.0, op-cost: 0.0, total-cost: 2.0]
+                                -- STREAM_PROJECT  |PARTITIONED|
+                                  exchange [cardinality: 2.0, op-cost: 0.0, total-cost: 2.0]
+                                  -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                    data-scan []<-[$$69, $$t] <- test.ColumnDataset [cardinality: 2.0, op-cost: 2.0, total-cost: 2.0]
+                                    -- DATASOURCE_SCAN  |PARTITIONED|
+                                      exchange [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                                      -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                        empty-tuple-source [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                                        -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results_cbo/column/pushdown/other-pushdowns/other-pushdowns.021.plan b/asterixdb/asterix-app/src/test/resources/runtimets/results_cbo/column/pushdown/other-pushdowns/other-pushdowns.021.plan
new file mode 100644
index 0000000..4e264fa
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results_cbo/column/pushdown/other-pushdowns/other-pushdowns.021.plan
@@ -0,0 +1,51 @@
+distribute result [$$68] [cardinality: 0.0, op-cost: 0.0, total-cost: 2.0]
+-- DISTRIBUTE_RESULT  |UNPARTITIONED|
+  exchange [cardinality: 0.0, op-cost: 0.0, total-cost: 2.0]
+  -- ONE_TO_ONE_EXCHANGE  |UNPARTITIONED|
+    project ([$$68]) [cardinality: 0.0, op-cost: 0.0, total-cost: 2.0]
+    -- STREAM_PROJECT  |UNPARTITIONED|
+      assign [$$68] <- [{"count": $$71}] [cardinality: 0.0, op-cost: 0.0, total-cost: 2.0]
+      -- ASSIGN  |UNPARTITIONED|
+        aggregate [$$71] <- [agg-sql-count(1)] [cardinality: 0.0, op-cost: 0.0, total-cost: 2.0]
+        -- AGGREGATE  |UNPARTITIONED|
+          exchange [cardinality: 0.0, op-cost: 0.0, total-cost: 2.0]
+          -- SORT_MERGE_EXCHANGE [$$66(ASC) ]  |PARTITIONED|
+            distinct ([$$66]) [cardinality: 0.0, op-cost: 0.0, total-cost: 2.0]
+            -- PRE_SORTED_DISTINCT_BY  |PARTITIONED|
+              exchange [cardinality: 0.0, op-cost: 0.0, total-cost: 2.0]
+              -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                order (ASC, $$66) [cardinality: 0.0, op-cost: 0.0, total-cost: 2.0]
+                -- STABLE_SORT [$$66(ASC)]  |PARTITIONED|
+                  exchange [cardinality: 0.0, op-cost: 0.0, total-cost: 2.0]
+                  -- HASH_PARTITION_EXCHANGE [$$66]  |PARTITIONED|
+                    project ([$$66]) [cardinality: 0.0, op-cost: 0.0, total-cost: 2.0]
+                    -- STREAM_PROJECT  |PARTITIONED|
+                      select (ge($$70, 3)) [cardinality: 0.0, op-cost: 0.0, total-cost: 2.0]
+                      -- STREAM_SELECT  |PARTITIONED|
+                        project ([$$66, $$70]) [cardinality: 2.0, op-cost: 0.0, total-cost: 2.0]
+                        -- STREAM_PROJECT  |PARTITIONED|
+                          subplan {
+                                    aggregate [$$70] <- [agg-sql-sum($$52)] [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                                    -- AGGREGATE  |LOCAL|
+                                      assign [$$52] <- [$$i.getField("count")] [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                                      -- ASSIGN  |LOCAL|
+                                        unnest $$i <- scan-collection($$72) [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                                        -- UNNEST  |LOCAL|
+                                          nested tuple source [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                                          -- NESTED_TUPLE_SOURCE  |LOCAL|
+                                 } [cardinality: 2.0, op-cost: 0.0, total-cost: 2.0]
+                          -- SUBPLAN  |PARTITIONED|
+                            project ([$$66, $$72]) [cardinality: 2.0, op-cost: 0.0, total-cost: 2.0]
+                            -- STREAM_PROJECT  |PARTITIONED|
+                              assign [$$66, $$72] <- [if-missing-or-null(to-object($$t), cast({  })).getField(0), $$t.getField("a1")] [cardinality: 2.0, op-cost: 0.0, total-cost: 2.0]
+                              -- ASSIGN  |PARTITIONED|
+                                project ([$$t]) [cardinality: 2.0, op-cost: 0.0, total-cost: 2.0]
+                                -- STREAM_PROJECT  |PARTITIONED|
+                                  exchange [cardinality: 2.0, op-cost: 0.0, total-cost: 2.0]
+                                  -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                    data-scan []<-[$$69, $$t] <- test.ColumnDataset [cardinality: 2.0, op-cost: 2.0, total-cost: 2.0]
+                                    -- DATASOURCE_SCAN  |PARTITIONED|
+                                      exchange [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                                      -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                        empty-tuple-source [cardinality: 0.0, op-cost: 0.0, total-cost: 0.0]
+                                        -- EMPTY_TUPLE_SOURCE  |PARTITIONED|