pass "isModificationQuery" around in cluster

arangod/Aql/ExecutionPlan.cpp

@@ -406,6 +406,7 @@ void ExecutionPlan::toVelocyPack(VPackBuilder& builder, Ast* ast,
   builder.add("estimatedCost", VPackValue(_root->getCost(nrItems)));
   builder.add("estimatedNrItems", VPackValue(nrItems));
   builder.add("initialize", VPackValue(_isResponsibleForInitialize));
+  builder.add("isModificationQuery", VPackValue(ast->query()->isModificationQuery()));
 
   builder.close();
 }

arangod/Aql/Query.cpp

@@ -199,6 +199,12 @@ Query::Query(
         << "options: " << options->slice().toJson();
   }
 
+  // adjust the _isModificationQuery value from the slice we got
+  auto s = _queryBuilder->slice().get("isModificationQuery");
+  if (s.isBoolean()) {
+    _isModificationQuery = s.getBoolean();
+  }
+
   _resourceMonitor.setMemoryLimit(_queryOptions.memoryLimit);
 }
 
@@ -236,6 +242,10 @@ Query* Query::clone(QueryPart part, bool withPlan) {
   clone->_resourceMonitor = _resourceMonitor;
   clone->_resourceMonitor.clear();
 
+  if (_isModificationQuery) {
+    clone->setIsModificationQuery();
+  }
+
   if (_plan != nullptr) {
     if (withPlan) {
       // clone the existing plan

arangod/Aql/Query.h

@@ -225,6 +225,9 @@ class Query {
   /// @brief get the plan for the query
   ExecutionPlan* plan() const { return _plan.get(); }
 
+  /// @brief whether or not a query is a modification query
+  bool isModificationQuery() const { return _isModificationQuery; }
+
   /// @brief mark a query as modification query
   void setIsModificationQuery() { _isModificationQuery = true; }