From 06cb81be3d860f67b8f26c3b988c6748f5ef7f89 Mon Sep 17 00:00:00 2001
From: Jan Christoph Uhde <ObiWahn@users.noreply.github.com>
Date: Tue, 26 Nov 2019 10:13:52 +0100
Subject: [PATCH] Bug fix 3.4/little weekend fix (#10526)

* create arena before using it

* try to avoid oom situation
---
 arangod/MMFiles/MMFilesHashIndex.cpp    | 1 +
 arangod/MMFiles/MMFilesHashIndex.h      | 6 ++++--
 arangod/MMFiles/MMFilesPrimaryIndex.cpp | 5 ++++-
 3 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/arangod/MMFiles/MMFilesHashIndex.cpp b/arangod/MMFiles/MMFilesHashIndex.cpp
index 559fab30ca..a0fa5923de 100644
--- a/arangod/MMFiles/MMFilesHashIndex.cpp
+++ b/arangod/MMFiles/MMFilesHashIndex.cpp
@@ -52,6 +52,7 @@ MMFilesHashIndexLookupBuilder::MMFilesHashIndexLookupBuilder(
     : _builder(trx),
       _usesIn(false),
       _isEmpty(false),
+      _mappingFieldConditionArena(),
       _mappingFieldCondition{_mappingFieldConditionArena},
       _inStorage(trx) {
   TRI_ASSERT(node->type == aql::NODE_TYPE_OPERATOR_NARY_AND);
diff --git a/arangod/MMFiles/MMFilesHashIndex.h b/arangod/MMFiles/MMFilesHashIndex.h
index 5ec364f3e3..00f0ea24a5 100644
--- a/arangod/MMFiles/MMFilesHashIndex.h
+++ b/arangod/MMFiles/MMFilesHashIndex.h
@@ -179,8 +179,10 @@ class MMFilesHashIndexLookupBuilder {
   bool _isEmpty;
   size_t _coveredFields;
 
-  SmallVector<arangodb::aql::AstNode const*> _mappingFieldCondition;
-  SmallVector<arangodb::aql::AstNode const*>::allocator_type::arena_type _mappingFieldConditionArena;
+  using MappingCondition =
+      SmallVector<arangodb::aql::AstNode const*>;
+  MappingCondition::allocator_type::arena_type _mappingFieldConditionArena;
+  MappingCondition _mappingFieldCondition;
 
   std::unordered_map<size_t, std::pair<size_t, std::vector<arangodb::velocypack::Slice>>> _inPosition;
   transaction::BuilderLeaser _inStorage;
diff --git a/arangod/MMFiles/MMFilesPrimaryIndex.cpp b/arangod/MMFiles/MMFilesPrimaryIndex.cpp
index 7875dce72b..87aaeaa042 100644
--- a/arangod/MMFiles/MMFilesPrimaryIndex.cpp
+++ b/arangod/MMFiles/MMFilesPrimaryIndex.cpp
@@ -21,8 +21,11 @@
 /// @author Dr. Frank Celler
 ////////////////////////////////////////////////////////////////////////////////
 
+#include <algorithm>
+
 #include "MMFilesPrimaryIndex.h"
 #include "Aql/AstNode.h"
+#include "Aql/ExecutionBlock.h"
 #include "Basics/Exceptions.h"
 #include "Basics/StaticStrings.h"
 #include "Basics/hashes.h"
@@ -162,7 +165,7 @@ bool MMFilesAllIndexIterator::next(LocalDocumentIdCallback const& cb, size_t lim
 
 bool MMFilesAllIndexIterator::nextDocument(DocumentCallback const& cb, size_t limit) {
   _documentIds.clear();
-  _documentIds.reserve(limit);
+  _documentIds.reserve((std::min)(limit, aql::ExecutionBlock::DefaultBatchSize()));
 
   bool done = false;
   while (limit > 0) {