diff --git a/arangod/VocBase/cleanup.cpp b/arangod/VocBase/cleanup.cpp
index 15d9920c5e..189b7e4de6 100644
--- a/arangod/VocBase/cleanup.cpp
+++ b/arangod/VocBase/cleanup.cpp
@@ -84,10 +84,9 @@ static void CleanupDocumentCollection (TRI_document_collection_t* document) {
   while (true) {
     TRI_barrier_list_t* container;
     TRI_barrier_t* element;
-    bool hasUnloaded = false;
 
     container = &document->_barrierList;
-    element = NULL;
+    element = nullptr;
 
     // check and remove all callback elements at the beginning of the list
     TRI_LockSpin(&container->_lock);
@@ -96,7 +95,7 @@ static void CleanupDocumentCollection (TRI_document_collection_t* document) {
     // if it is a TRI_BARRIER_ELEMENT, it means that there is still a reference held
     // to document data in a datafile. We must then not unload or remove a file
 
-    if (container->_begin == NULL ||
+    if (container->_begin == nullptr ||
         container->_begin->_type == TRI_BARRIER_ELEMENT ||
         container->_begin->_type == TRI_BARRIER_COLLECTION_REPLICATION ||
         container->_begin->_type == TRI_BARRIER_COLLECTION_COMPACTION ||
@@ -122,16 +121,25 @@ static void CleanupDocumentCollection (TRI_document_collection_t* document) {
     // any newer TRI_BARRIER_ELEMENTS will always reference data inside other datafiles.
 
     element = container->_begin;
-    assert(element);
+    assert(element != nullptr);
+
+    if (element->_type == TRI_BARRIER_COLLECTION_UNLOAD_CALLBACK) {
+      // check if we can really unload, this is only the case if the collection's WAL markers
+      // were fully collected
+      if (! TRI_IsFullyCollectedDocumentCollection(document)) {
+        TRI_UnlockSpin(&container->_lock);
+        return;
+      }
+    }
 
     // found an element to go on with
     container->_begin = element->_next;
 
-    if (element->_next == NULL) {
-      container->_end = NULL;
+    if (element->_next == nullptr) {
+      container->_end = nullptr;
     }
     else {
-      element->_next->_prev = NULL;
+      element->_next->_prev = nullptr;
     }
 
     // yes, we can release the lock here
@@ -161,10 +169,8 @@ static void CleanupDocumentCollection (TRI_document_collection_t* document) {
     }
     else if (element->_type == TRI_BARRIER_COLLECTION_UNLOAD_CALLBACK) {
       // collection is unloaded
-      TRI_barrier_collection_cb_t* ce;
-
-      ce = (TRI_barrier_collection_cb_t*) element;
-      hasUnloaded = ce->callback(ce->_collection, ce->_data);
+      TRI_barrier_collection_cb_t* ce = (TRI_barrier_collection_cb_t*) element;
+      bool hasUnloaded = ce->callback(ce->_collection, ce->_data);
       TRI_Free(TRI_UNKNOWN_MEM_ZONE, element);
 
       if (hasUnloaded) {
@@ -174,10 +180,8 @@ static void CleanupDocumentCollection (TRI_document_collection_t* document) {
     }
     else if (element->_type == TRI_BARRIER_COLLECTION_DROP_CALLBACK) {
       // collection is dropped
-      TRI_barrier_collection_cb_t* ce;
-
-      ce = (TRI_barrier_collection_cb_t*) element;
-      hasUnloaded = ce->callback(ce->_collection, ce->_data);
+      TRI_barrier_collection_cb_t* ce = (TRI_barrier_collection_cb_t*) element;
+      bool hasUnloaded = ce->callback(ce->_collection, ce->_data);
       TRI_Free(TRI_UNKNOWN_MEM_ZONE, element);
 
       if (hasUnloaded) {
diff --git a/arangod/VocBase/document-collection.cpp b/arangod/VocBase/document-collection.cpp
index ee5235bb58..9c253d31c9 100644
--- a/arangod/VocBase/document-collection.cpp
+++ b/arangod/VocBase/document-collection.cpp
@@ -2297,14 +2297,14 @@ static TRI_doc_collection_info_t* Figures (TRI_document_collection_t* document)
   // prefill with 0's to init counters
   TRI_doc_collection_info_t* info = static_cast<TRI_doc_collection_info_t*>(TRI_Allocate(TRI_UNKNOWN_MEM_ZONE, sizeof(TRI_doc_collection_info_t), true));
 
-  if (info == NULL) {
-    return NULL;
+  if (info == nullptr) {
+    return nullptr;
   }
     
   for (size_t i = 0;  i < document->_datafileInfo._nrAlloc;  ++i) {
     TRI_doc_datafile_info_t* d = static_cast<TRI_doc_datafile_info_t*>(document->_datafileInfo._table[i]);
 
-    if (d != NULL) {
+    if (d != nullptr) {
       info->_numberAlive        += d->_numberAlive;
       info->_numberDead         += d->_numberDead;
       info->_numberTransaction  += d->_numberTransaction; // not used here (only in compaction)
@@ -2346,12 +2346,12 @@ static TRI_doc_collection_info_t* Figures (TRI_document_collection_t* document)
 
   // add index information
   info->_numberIndexes = 0;
-  info->_sizeIndexes = 0;
+  info->_sizeIndexes   = 0;
 
   for (size_t i = 0; i < document->_allIndexes._length; ++i) { 
     TRI_index_t const* idx = static_cast<TRI_index_t const*>(TRI_AtVectorPointer(&document->_allIndexes, i)); 
 
-    if (idx->memory != NULL) {
+    if (idx->memory != nullptr) {
       info->_sizeIndexes += idx->memory(idx);
     }
     info->_numberIndexes++; 
@@ -2370,12 +2370,12 @@ static TRI_doc_collection_info_t* Figures (TRI_document_collection_t* document)
 
 static bool InitDocumentCollection (TRI_document_collection_t* document,
                                     TRI_shaper_t* shaper) {
-  TRI_index_t* primaryIndex;
-  int res;
+  document->_cleanupIndexes   = false;
 
-  document->_cleanupIndexes = false;
+  document->_lastWrittenId    = 0;
+  document->_lastCollectedId  = 0;
 
-  res = TRI_InitPrimaryCollection(document, shaper);
+  int res = TRI_InitPrimaryCollection(document, shaper);
 
   if (res != TRI_ERROR_NO_ERROR) {
     TRI_DestroyCollection(&document->base);
@@ -2386,7 +2386,7 @@ static bool InitDocumentCollection (TRI_document_collection_t* document,
 
   document->_headersPtr = TRI_CreateSimpleHeaders();  // ONLY IN CREATE COLLECTION
 
-  if (document->_headersPtr == NULL) {  // ONLY IN CREATE COLLECTION
+  if (document->_headersPtr == nullptr) {  // ONLY IN CREATE COLLECTION
     TRI_DestroyPrimaryCollection(document);
 
     return false;
@@ -2402,9 +2402,9 @@ static bool InitDocumentCollection (TRI_document_collection_t* document,
   }
 
   // create primary index
-  primaryIndex = TRI_CreatePrimaryIndex(document);
+  TRI_index_t* primaryIndex = TRI_CreatePrimaryIndex(document);
 
-  if (primaryIndex == NULL) {
+  if (primaryIndex == nullptr) {
     TRI_DestroyVectorPointer(&document->_allIndexes);
     TRI_DestroyPrimaryCollection(document);
     TRI_set_errno(TRI_ERROR_OUT_OF_MEMORY);
@@ -2429,7 +2429,7 @@ static bool InitDocumentCollection (TRI_document_collection_t* document,
 
     edgesIndex = TRI_CreateEdgeIndex(document, document->base._info._cid);
 
-    if (edgesIndex == NULL) {
+    if (edgesIndex == nullptr) {
       TRI_FreeIndex(primaryIndex);
       TRI_DestroyVectorPointer(&document->_allIndexes);
       TRI_DestroyPrimaryCollection(document);
@@ -2474,6 +2474,8 @@ static bool InitDocumentCollection (TRI_document_collection_t* document,
 
   // we do not require an initial journal
   document->_rotateRequested       = false;
+  
+  TRI_InitSpin(&document->_idLock);
 
   return true;
 }
@@ -2640,22 +2642,23 @@ TRI_document_collection_t* TRI_CreateDocumentCollection (TRI_vocbase_t* vocbase,
 ////////////////////////////////////////////////////////////////////////////////
 
 void TRI_DestroyDocumentCollection (TRI_document_collection_t* document) {
-  size_t i, n;
-
   TRI_DestroyCondition(&document->_journalsCondition);
 
   TRI_FreeSimpleHeaders(document->_headersPtr);  // PROTECTED because collection is already closed
 
   // free memory allocated for indexes
-  n = document->_allIndexes._length;
-  for (i = 0 ; i < n ; ++i) {
+  size_t const n = document->_allIndexes._length;
+  for (size_t i = 0 ; i < n ; ++i) {
     TRI_index_t* idx = (TRI_index_t*) document->_allIndexes._buffer[i];
 
     TRI_FreeIndex(idx);
   }
+
   // free index vector
   TRI_DestroyVectorPointer(&document->_allIndexes);
   TRI_DestroyVector(&document->_failedTransactions);
+  
+  TRI_DestroySpin(&document->_idLock);
 
   TRI_DestroyPrimaryCollection(document);
 }
@@ -2673,6 +2676,42 @@ void TRI_FreeDocumentCollection (TRI_document_collection_t* document) {
 // --SECTION--                                                  public functions
 // -----------------------------------------------------------------------------
 
+////////////////////////////////////////////////////////////////////////////////
+/// @brief update the "last written" value for a collection
+////////////////////////////////////////////////////////////////////////////////
+
+void TRI_SetLastWrittenDocumentCollection (TRI_document_collection_t* document, 
+                                           TRI_voc_tick_t id) {
+  // the id is the id of the last WAL file that contains data for the collection
+  TRI_LockSpin(&document->_idLock);
+  document->_lastWrittenId = id;
+  TRI_UnlockSpin(&document->_idLock);
+}
+
+////////////////////////////////////////////////////////////////////////////////
+/// @brief update the "last collected" value for a collection
+////////////////////////////////////////////////////////////////////////////////
+
+void TRI_SetLastCollectedDocumentCollection (TRI_document_collection_t* document, 
+                                           TRI_voc_tick_t id) {
+  // the id is the id of the last WAL file that contains data for the collection
+  TRI_LockSpin(&document->_idLock);
+  document->_lastCollectedId = id;
+  TRI_UnlockSpin(&document->_idLock);
+}
+
+////////////////////////////////////////////////////////////////////////////////
+/// @brief whether or not markers of a collection were fully collected
+////////////////////////////////////////////////////////////////////////////////
+
+bool TRI_IsFullyCollectedDocumentCollection (TRI_document_collection_t* document) { 
+  TRI_LockSpin(&document->_idLock);
+  bool result = (document->_lastCollectedId == document->_lastWrittenId);
+  TRI_UnlockSpin(&document->_idLock);
+
+  return result;
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 /// @brief initialises a primary collection
 ////////////////////////////////////////////////////////////////////////////////
@@ -3182,7 +3221,7 @@ TRI_document_collection_t* TRI_OpenDocumentCollection (TRI_vocbase_t* vocbase,
   if (TRI_IsTraceLogging(__FILE__)) {
     TRI_DebugDatafileInfoPrimaryCollection(document);
   }
-
+  
   return document;
 }
 
diff --git a/arangod/VocBase/document-collection.h b/arangod/VocBase/document-collection.h
index 631cc088aa..8308d11778 100644
--- a/arangod/VocBase/document-collection.h
+++ b/arangod/VocBase/document-collection.h
@@ -56,6 +56,7 @@ struct TRI_document_edge_s;
 struct TRI_index_s;
 struct TRI_json_s;
 struct TRI_key_generator_s;
+
 namespace triagens {
   namespace arango {
     class TransactionBase;
@@ -321,6 +322,11 @@ typedef struct TRI_document_collection_s {
   TRI_read_write_lock_t        _compactionLock;
   double                       _lastCompaction;
 
+  // this lock protected _lastWrittenId and _lastCollectedId
+  TRI_spin_t                   _idLock;
+  TRI_voc_tick_t               _lastWrittenId;
+  TRI_voc_tick_t               _lastCollectedId;
+
   // .............................................................................
   // this condition variable protects the _journalsCondition
   // .............................................................................
@@ -589,6 +595,26 @@ void TRI_FreeDocumentCollection (TRI_document_collection_t*);
 // --SECTION--                                                  public functions
 // -----------------------------------------------------------------------------
 
+////////////////////////////////////////////////////////////////////////////////
+/// @brief update the "last written" value for a collection
+////////////////////////////////////////////////////////////////////////////////
+
+void TRI_SetLastWrittenDocumentCollection (TRI_document_collection_t*, 
+                                           TRI_voc_tick_t);
+
+////////////////////////////////////////////////////////////////////////////////
+/// @brief update the "last collected" value for a collection
+////////////////////////////////////////////////////////////////////////////////
+
+void TRI_SetLastCollectedDocumentCollection (TRI_document_collection_t*, 
+                                             TRI_voc_tick_t);
+
+////////////////////////////////////////////////////////////////////////////////
+/// @brief whether or not markers of a collection were fully collected
+////////////////////////////////////////////////////////////////////////////////
+
+bool TRI_IsFullyCollectedDocumentCollection (TRI_document_collection_t*); 
+
 ////////////////////////////////////////////////////////////////////////////////
 /// @brief create an index, based on a JSON description
 ////////////////////////////////////////////////////////////////////////////////
diff --git a/arangod/VocBase/transaction.cpp b/arangod/VocBase/transaction.cpp
index f9fad6293f..31bfd3687c 100644
--- a/arangod/VocBase/transaction.cpp
+++ b/arangod/VocBase/transaction.cpp
@@ -890,11 +890,15 @@ int TRI_AddOperationTransaction (triagens::wal::DocumentOperation& operation,
     copy->handle();
   }
 
+  TRI_document_collection_t* document = trxCollection->_collection->_collection;
+
   if (operation.rid > 0) {
-    TRI_document_collection_t* document = trxCollection->_collection->_collection;
     TRI_SetRevisionDocumentCollection(document, operation.rid, false);
   }
 
+  // update logfile id
+  TRI_SetLastWrittenDocumentCollection(document, slotInfo.slot->logfileId());
+
   return TRI_ERROR_NO_ERROR;
 }
 
diff --git a/arangod/VocBase/voc-shaper.cpp b/arangod/VocBase/voc-shaper.cpp
index 887e183739..fcb50bee9a 100644
--- a/arangod/VocBase/voc-shaper.cpp
+++ b/arangod/VocBase/voc-shaper.cpp
@@ -205,6 +205,8 @@ static TRI_shape_aid_t FindOrCreateAttributeByName (TRI_shaper_t* shaper,
     // enter into the dictionaries
     f = TRI_InsertKeyAssociativeSynced(&s->_attributeNames, name, const_cast<void*>(slotInfo.mem), false);
     assert(f == nullptr);
+    
+    TRI_SetLastWrittenDocumentCollection(document, slotInfo.slot->logfileId());
   }
 
   return aid;
@@ -356,6 +358,8 @@ static TRI_shape_t const* FindShape (TRI_shaper_t* shaper,
 
     f = TRI_InsertElementAssociativeSynced(&s->_shapeDictionary, (void*) m, false);
     assert(f == nullptr);
+    
+    TRI_SetLastWrittenDocumentCollection(document, slotInfo.slot->logfileId());
   }
 
   TRI_Free(TRI_UNKNOWN_MEM_ZONE, shape);
diff --git a/arangod/Wal/CollectorThread.cpp b/arangod/Wal/CollectorThread.cpp
index a8c13d331b..13005f0bdb 100644
--- a/arangod/Wal/CollectorThread.cpp
+++ b/arangod/Wal/CollectorThread.cpp
@@ -417,7 +417,7 @@ int CollectorThread::collect (Logfile* logfile) {
       CollectorCache cache;
 
       // TODO: handle errors indicated by transferMarkers!
-      transferMarkers(cid, state.collections[cid], sortedOperations, cache);
+      transferMarkers(logfile->id(), cid, state.collections[cid], sortedOperations, cache);
     }
   }
 
@@ -434,7 +434,8 @@ int CollectorThread::collect (Logfile* logfile) {
 /// @brief transfer markers into a collection
 ////////////////////////////////////////////////////////////////////////////////
 
-int CollectorThread::transferMarkers (TRI_voc_cid_t collectionId,
+int CollectorThread::transferMarkers (Logfile::IdType logfileId,
+                                      TRI_voc_cid_t collectionId,
                                       TRI_voc_tick_t databaseId,
                                       OperationsType const& operations,
                                       CollectorCache& cache) {
@@ -674,6 +675,8 @@ int CollectorThread::transferMarkers (TRI_voc_cid_t collectionId,
   // now sync the datafile
   int res = syncCollection(document);
 
+  TRI_SetLastCollectedDocumentCollection(document, logfileId);
+
   TRI_ReleaseCollectionVocBase(vocbase, collection);
 
   return res;
diff --git a/arangod/Wal/CollectorThread.h b/arangod/Wal/CollectorThread.h
index 4306b50e9f..beeefb1efb 100644
--- a/arangod/Wal/CollectorThread.h
+++ b/arangod/Wal/CollectorThread.h
@@ -33,6 +33,7 @@
 #include "Basics/Thread.h"
 #include "VocBase/datafile.h"
 #include "VocBase/voc-types.h"
+#include "Wal/Logfile.h"
 
 struct TRI_datafile_s;
 struct TRI_df_marker_s;
@@ -178,7 +179,8 @@ namespace triagens {
 /// @brief transfer markers into a collection
 ////////////////////////////////////////////////////////////////////////////////
 
-        int transferMarkers (TRI_voc_cid_t,
+        int transferMarkers (triagens::wal::Logfile::IdType,
+                             TRI_voc_cid_t,
                              TRI_voc_tick_t,
                              OperationsType const&,
                              CollectorCache&);
diff --git a/js/common/tests/shell-document.js b/js/common/tests/shell-document.js
index d9e7bff933..00ba5daed5 100644
--- a/js/common/tests/shell-document.js
+++ b/js/common/tests/shell-document.js
@@ -33,6 +33,20 @@ var ERRORS = arangodb.errors;
 var db = arangodb.db;
 var wait = require("internal").wait;
 
+// -----------------------------------------------------------------------------
+// --SECTION--                                                  helper functions
+// -----------------------------------------------------------------------------
+      
+function waitUnload (collection) {      
+  collection.unload();
+  /*
+  while (collection.status() != arangodb.ArangoCollection.STATUS_UNLOADED) { 
+    wait(1);
+  }
+  assertEqual(arangodb.ArangoCollection.STATUS_UNLOADED, collection.status());
+  */
+}
+
 // -----------------------------------------------------------------------------
 // --SECTION--                                                collection methods
 // -----------------------------------------------------------------------------
@@ -366,11 +380,7 @@ function CollectionDocumentSuite () {
       d1 = null;
       d2 = null;
 
-      collection.unload();
-      while (collection.status() != arangodb.ArangoCollection.STATUS_UNLOADED) { 
-        wait(1);
-      }
-      assertEqual(arangodb.ArangoCollection.STATUS_UNLOADED, collection.status());
+      waitUnload(collection);
 
       collection.load();
 
@@ -403,11 +413,7 @@ function CollectionDocumentSuite () {
       d1 = null;
       d2 = null;
 
-      collection.unload();
-      while (collection.status() != arangodb.ArangoCollection.STATUS_UNLOADED) { 
-        wait(1);
-      }
-      assertEqual(arangodb.ArangoCollection.STATUS_UNLOADED, collection.status());
+      waitUnload(collection);
 
       collection.load();
 
@@ -435,11 +441,7 @@ function CollectionDocumentSuite () {
 
       assertEqual(0, collection.count());
 
-      collection.unload();
-      while (collection.status() != arangodb.ArangoCollection.STATUS_UNLOADED) { 
-        wait(1);
-      }
-      assertEqual(arangodb.ArangoCollection.STATUS_UNLOADED, collection.status());
+      waitUnload(collection);
 
       collection.load();
 
@@ -475,11 +477,7 @@ function CollectionDocumentSuite () {
 
       assertEqual(1, collection.count());
 
-      collection.unload();
-      while (collection.status() != arangodb.ArangoCollection.STATUS_UNLOADED) { 
-        wait(1);
-      }
-      assertEqual(arangodb.ArangoCollection.STATUS_UNLOADED, collection.status());
+      waitUnload(collection);
 
       collection.load();
 
@@ -520,11 +518,7 @@ function CollectionDocumentSuite () {
       assertEqual(0, doc.value);
       doc = null;
 
-      collection.unload();
-      while (collection.status() != arangodb.ArangoCollection.STATUS_UNLOADED) { 
-        wait(1);
-      }
-      assertEqual(arangodb.ArangoCollection.STATUS_UNLOADED, collection.status());
+      waitUnload(collection);
 
       collection.load();