diff --git a/arangod/Indexes/HashIndex.cpp b/arangod/Indexes/HashIndex.cpp
index e7682226e1..c5b3c0a112 100644
--- a/arangod/Indexes/HashIndex.cpp
+++ b/arangod/Indexes/HashIndex.cpp
@@ -204,9 +204,9 @@ HashIndex::HashIndex (TRI_idx_iid_t iid,
   }
     
   std::unique_ptr<HashElementFunc> func(new HashElementFunc(_paths.size()));
+  std::unique_ptr<IsEqualElementElementByKey> compare(new IsEqualElementElementByKey(_paths.size()));
 
   if (unique) {
-    std::unique_ptr<IsEqualElementElementByKey> compare(new IsEqualElementElementByKey(_paths.size()));
     std::unique_ptr<TRI_HashArray_t> array(new TRI_HashArray_t(HashKey,
                                                                *(func.get()),
                                                                IsEqualKeyElementHash,
@@ -221,8 +221,6 @@ HashIndex::HashIndex (TRI_idx_iid_t iid,
   else {
     _multiArray = nullptr;
       
-    std::unique_ptr<IsEqualElementElementByKey> compare(new IsEqualElementElementByKey(_paths.size()));
-
     std::unique_ptr<TRI_HashArrayMulti_t> array(new TRI_HashArrayMulti_t(HashKey, 
                                                                          *(func.get()),
                                                                          IsEqualKeyElement,
@@ -234,9 +232,9 @@ HashIndex::HashIndex (TRI_idx_iid_t iid,
       
     _multiArray = new HashIndex::MultiArray(array.get(), func.get(), compare.get());
 
-    compare.release();
     array.release();
   }
+  compare.release();
 
   func.release();
 }
@@ -552,6 +550,7 @@ int HashIndex::insertMulti (TRI_doc_mptr_t const* doc,
     for (auto& hashElement : elements) {
       FreeElement(hashElement);
     }
+    return res;
   }
 
   auto work = [this] (TRI_index_element_t* element, bool isRollback) -> int {
diff --git a/lib/Basics/AssocMulti.h b/lib/Basics/AssocMulti.h
index dd52e2644e..03948bcf5b 100644
--- a/lib/Basics/AssocMulti.h
+++ b/lib/Basics/AssocMulti.h
@@ -36,12 +36,12 @@
 // #define TRI_CHECK_MULTI_POINTER_HASH 1
 
 #include "Basics/Common.h"
-#include "Basics/prime-numbers.h"
 #include "Basics/JsonHelper.h"
 #include "Basics/logging.h"
+#include "Basics/memory-map.h"
 #include "Basics/Mutex.h"
 #include "Basics/MutexLocker.h"
-#include "Basics/memory-map.h"
+#include "Basics/prime-numbers.h"
 
 namespace triagens {
   namespace basics {
diff --git a/lib/Basics/AssocUnique.h b/lib/Basics/AssocUnique.h
index d2e5593b26..8a592616e4 100644
--- a/lib/Basics/AssocUnique.h
+++ b/lib/Basics/AssocUnique.h
@@ -36,7 +36,9 @@
 #include "Basics/gcd.h"
 #include "Basics/JsonHelper.h"
 #include "Basics/logging.h"
+#include "Basics/memory-map.h"
 #include "Basics/MutexLocker.h"
+#include "Basics/prime-numbers.h"
 #include "Basics/random.h"
 
 namespace triagens {
@@ -230,9 +232,21 @@ namespace triagens {
 
             TRI_ASSERT(targetSize > 0);
 
+            targetSize = TRI_NearPrime(targetSize);
+
             // This might throw, is catched outside
             b._table = new Element* [targetSize];
 
+#ifdef __linux__
+            if (b._nrAlloc > 1000000) {
+              uintptr_t mem = reinterpret_cast<uintptr_t>(b._table);
+              uintptr_t pageSize = getpagesize();
+              mem = (mem / pageSize) * pageSize;
+              void* memptr = reinterpret_cast<void*>(mem);
+              TRI_MMFileAdvise(memptr, b._nrAlloc * sizeof(Element*),
+                               TRI_MADVISE_RANDOM);
+            }
+#endif
             for (uint64_t i = 0; i < targetSize; i++) {
               b._table[i] = nullptr;
             }
@@ -390,11 +404,14 @@ namespace triagens {
 ////////////////////////////////////////////////////////////////////////////////
 
           int resize (size_t size) {
+            size /= _buckets.size();
             for (auto& b : _buckets) {
+              if (2 * (2 * size + 1) < 3 * b._nrUsed) {
+                return TRI_ERROR_BAD_PARAMETER;
+              }
+
               try {
-                resizeInternal(b,
-                    (uint64_t) (3 * size / 2 + 1) / _buckets.size(), 
-                    false);
+                resizeInternal(b, 2 * size + 1, false);
               }
               catch (...) {
                 return TRI_ERROR_OUT_OF_MEMORY;