Fix a bug where a cte producer was dropped due to errors creating the…

… cloned cte dependency graph in SimplifyPlanWithEmptyInput optimizer

Fixed a bug in removeCteProducersFromCteDependencyGraph function of Sequence node, currently used by SimplifyPlanWithEmptyInput optimizer where a cte producer was dropped from the graph (and from scheduling) if there were no edges leading from it leading to wrong results

presto-hive/src/test/java/com/facebook/presto/hive/TestCteExecution.java

@@ -71,6 +71,18 @@ public void testCteExecutionWhereOneCteRemovedBySimplifyEmptyInputRule()
                         sql));
     }
 
+    @Test
+    public void testCteExecutionWhereChildPlanRemovedBySimplifyEmptyInputRule()
+    {
+        String sql = "WITH t as(SELECT * FROM orders LEFT JOIN (select orderkey from orders where false) ON TRUE) " +
+                "SELECT * FROM t";
+        QueryRunner queryRunner = getQueryRunner();
+        compareResults(queryRunner.execute(getMaterializedSession(),
+                        sql),
+                queryRunner.execute(getSession(),
+                        sql));
+    }
+
     @Test
     public void testSimplePersistentCte()
     {

presto-main/src/main/java/com/facebook/presto/sql/planner/plan/SequenceNode.java

@@ -34,6 +34,7 @@
 import java.util.Optional;
 import java.util.Set;
 import java.util.stream.Collectors;
+import java.util.stream.IntStream;
 
 import static com.google.common.base.Preconditions.checkArgument;
 
@@ -69,6 +70,9 @@ public SequenceNode(Optional<SourceLocation> sourceLocation,
         this.cteProducers = ImmutableList.copyOf(cteProducerList);
         this.primarySource = primarySource;
         checkArgument(cteDependencyGraph.isDirected(), "Sequence Node expects a directed graph");
+        IntStream.range(0, cteProducerList.size())
+                .forEach(i -> checkArgument(cteDependencyGraph.nodes().contains(i),
+                        "Sequence Node Error: The cteProducer at index " + i + " is missing in the cte dependency graph."));
         this.cteDependencyGraph = ImmutableGraph.copyOf(cteDependencyGraph);
     }
 
@@ -121,6 +125,9 @@ public Graph<Integer> getCteDependencyGraph()
     // Returns a Graph after removing indexes
     public Graph<Integer> removeCteProducersFromCteDependencyGraph(Set<Integer> indexesToRemove)
     {
+        if (indexesToRemove.isEmpty()) {
+            return ImmutableGraph.copyOf(getCteDependencyGraph());
+        }
         Graph<Integer> originalGraph = getCteDependencyGraph();
         MutableGraph newCteDependencyGraph = GraphBuilder.from(getCteDependencyGraph()).build();
         Map<Integer, Integer> indexMapping = new HashMap<>();
@@ -138,6 +145,7 @@ public Graph<Integer> removeCteProducersFromCteDependencyGraph(Set<Integer> inde
         for (int oldIndex : originalGraph.nodes()) {
             if (!indexesToRemove.contains(oldIndex)) {
                 Integer newIndex = indexMapping.get(oldIndex);
+                newCteDependencyGraph.addNode(newIndex);
                 for (Integer successor : originalGraph.successors(oldIndex)) {
                     if (!indexesToRemove.contains(successor)) {
                         Integer newSuccessorIndex = indexMapping.get(successor);

presto-main/src/test/java/com/facebook/presto/cost/TestCostCalculator.java

@@ -71,6 +71,7 @@
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.graph.GraphBuilder;
+import com.google.common.graph.MutableGraph;
 import org.testng.annotations.AfterClass;
 import org.testng.annotations.BeforeClass;
 import org.testng.annotations.Test;
@@ -528,12 +529,16 @@ public void testSequence()
                 cteConsumerNode2,
                 JoinDistributionType.PARTITIONED,
                 "orderkey", "custkey");
+        MutableGraph<Integer> sequenceGraph = GraphBuilder.directed().build();
+        // Add indexes to the graph
+        sequenceGraph.addNode(0);
+        sequenceGraph.addNode(1);
         SequenceNode sequenceNode = new SequenceNode(
                 Optional.empty(),
                 new PlanNodeId("sequence"),
                 ImmutableList.of(cteProducerNode1, cteProducerNode2),
                 joinNode,
-                GraphBuilder.directed().build());
+                sequenceGraph);
 
         // Define cost of sequence children
         Map<String, PlanCostEstimate> costs = ImmutableMap.of(