@@ -97,9 +97,9 @@ public class RulePlanUnions implements OptimizerRule {
             
             boolean all = unionNode.hasBooleanProperty(NodeConstants.Info.USE_ALL);
             Operation op = (Operation)unionNode.getProperty(NodeConstants.Info.SET_OPERATION);
-            
-            collectUnionSources(metadata, capabilitiesFinder, unionNode, sourceNodes, all, op);
-            
+
+            List<PlanNode> childrenToKeep = collectUnionSources(metadata, capabilitiesFinder, unionNode, sourceNodes, all, op);
+
             if (sourceNodes.size() == 1) {
                 continue;
             }
@@ -132,6 +132,7 @@ public class RulePlanUnions implements OptimizerRule {
             
             unionNode.removeAllChildren();
             unionNode.addChildren(tempRoot.removeAllChildren());
+            unionNode.addChildren(childrenToKeep);
         }
     }
 
@@ -159,12 +160,13 @@ public class RulePlanUnions implements OptimizerRule {
     /**
      * TODO: union and intersect are associative
      */
-    private void collectUnionSources(QueryMetadataInterface metadata,
-                                     CapabilitiesFinder capabilitiesFinder,
-                                     PlanNode unionNode,
-                                     Map<Object, List<PlanNode>> sourceNodes,
-                                     boolean all, Operation setOp) throws QueryMetadataException,
+    private List<PlanNode> collectUnionSources(QueryMetadataInterface metadata,
+                                               CapabilitiesFinder capabilitiesFinder,
+                                               PlanNode unionNode,
+                                               Map<Object, List<PlanNode>> sourceNodes,
+                                               boolean all, Operation setOp) throws QueryMetadataException,
                                                  TeiidComponentException {
+        List<PlanNode> childrenToKeep = new ArrayList<>();
         for (PlanNode child : unionNode.getChildren()) {
             if (child.getType() == NodeConstants.Types.SET_OP) {
             	if (!all && Operation.UNION == child.getProperty(NodeConstants.Info.SET_OPERATION)) {
@@ -183,6 +185,7 @@ public class RulePlanUnions implements OptimizerRule {
                     }
                 } else { //recursively optimize
                     optimizeUnions(child, metadata, capabilitiesFinder);
+                    childrenToKeep.add(child);
                 }
             } else {  //this must be a source, see if it has a consistent access node
                 List<PlanNode> accessNodes = NodeEditor.findAllNodes(child, NodeConstants.Types.ACCESS);
@@ -194,9 +197,11 @@ public class RulePlanUnions implements OptimizerRule {
                 if (id == null) {
                     //recursively optimize below this point
                     optimizeUnions(child, metadata, capabilitiesFinder);
+                    childrenToKeep.add(child);
                 }
             }
         }
+        return childrenToKeep;
     }
 
     private Object getModelId(QueryMetadataInterface metadata,