diff --git a/3rdParty/velocypack/include/velocypack/Builder.h b/3rdParty/velocypack/include/velocypack/Builder.h
index 9429b585d4..a209056d8f 100644
--- a/3rdParty/velocypack/include/velocypack/Builder.h
+++ b/3rdParty/velocypack/include/velocypack/Builder.h
@@ -63,11 +63,11 @@ namespace arangodb {
       private:
 
         Buffer<uint8_t> _buffer;  // Here we collect the result
-        uint8_t*             _start;   // Always points to the start of _buffer
-        ValueLength          _size;    // Always contains the size of _buffer
-        ValueLength          _pos;     // the append position, always <= _size
-        bool                 _attrWritten;  // indicates that an attribute name
-                                            // in an object has been written
+        uint8_t*        _start;   // Always points to the start of _buffer
+        ValueLength     _size;    // Always contains the size of _buffer
+        ValueLength     _pos;     // the append position, always <= _size
+        bool            _attrWritten;  // indicates that an attribute name
+                                       // in an object has been written
         std::vector<ValueLength>              _stack;  // Start positions of
                                                        // open objects/arrays
         std::vector<std::vector<ValueLength>> _index;  // Indices for starts
@@ -92,7 +92,7 @@ namespace arangodb {
         // allocations. In the beginning, the _stack is empty, which
         // allows to build a sequence of unrelated VPack objects in the
         // buffer. Whenever the stack is empty, one can use the start,
-        // size and stealTo methods to get out the ready built VPack
+        // size and slice methods to get out the ready built VPack
         // object(s).
 
         void reserveSpace (ValueLength len) {
@@ -145,15 +145,9 @@ namespace arangodb {
         ~Builder () {
         }
 
-        Builder (Builder const& that) {
-          _buffer = that._buffer;
-          _start = _buffer.data();
-          _size = _buffer.size();
-          _pos = that._pos;
-          _attrWritten = that._attrWritten;
-          _stack = that._stack;
-          _index = that._index;
-          options = that.options;
+        Builder (Builder const& that) 
+          : _buffer(that._buffer), _start(_buffer.data()), _size(_buffer.size()), _pos(that._pos),
+            _attrWritten(that._attrWritten), _stack(that._stack), _index(that._index), options(that.options) {
         }
 
         Builder& operator= (Builder const& that) {
@@ -233,17 +227,23 @@ namespace arangodb {
         }
 
         // Add a subvalue into an object from a Value:
-        void add (std::string const& attrName, Value const& sub);
+        uint8_t* add (std::string const& attrName, Value const& sub);
+        
+        // Add a subvalue into an object from a Slice:
+        uint8_t* add (std::string const& attrName, Slice const& sub);
 
         // Add a subvalue into an object from a ValuePair:
         uint8_t* add (std::string const& attrName, ValuePair const& sub);
 
         // Add a subvalue into an array from a Value:
-        void add (Value const& sub);
+        uint8_t* add (Value const& sub);
+        
+        // Add a slice to an array
+        uint8_t* add (Slice const& sub);
 
         // Add a subvalue into an array from a ValuePair:
         uint8_t* add (ValuePair const& sub);
-
+        
         // Seal the innermost array or object:
         void close ();
 
@@ -365,6 +365,46 @@ namespace arangodb {
 
       private:
 
+        template<typename T>
+        uint8_t* addInternal (T const& sub) {
+          if (! _stack.empty()) {
+            ValueLength& tos = _stack.back();
+            if (_start[tos] != 0x06 && _start[tos] != 0x0b) {
+              throw Exception(Exception::BuilderNeedOpenObject);
+            }
+            if (_start[tos] == 0x0b) {  // Object
+              if (! _attrWritten && ! sub.isString()) {
+                throw Exception(Exception::BuilderNeedOpenObject);
+              }
+              if (! _attrWritten) {
+                reportAdd(tos);
+              }
+              _attrWritten = ! _attrWritten;
+            }
+            else {  // Array
+              reportAdd(tos);
+            }
+          }
+          return set(sub);
+        }
+  
+        template<typename T>
+        uint8_t* addInternal (std::string const& attrName, T const& sub) {
+          if (_attrWritten) {
+            throw Exception(Exception::InternalError, "Attribute name already written");
+          }
+          if (! _stack.empty()) {
+            ValueLength& tos = _stack.back();
+            if (_start[tos] != 0x06 &&
+                _start[tos] != 0x0b) {
+              throw Exception(Exception::BuilderNeedOpenObject);
+            }
+            reportAdd(tos);
+          }
+          set(Value(attrName, ValueType::String));
+          return set(sub);
+        }
+
         void addCompoundValue (uint8_t type) {
           reserveSpace(9);
           // an array is started:
@@ -378,10 +418,12 @@ namespace arangodb {
           _pos += 8;    // Will be filled later with bytelength and nr subs
         }
 
-        void set (Value const& item);
+        uint8_t* set (Value const& item);
 
         uint8_t* set (ValuePair const& pair);
         
+        uint8_t* set (Slice const& item);
+        
         void reportAdd (ValueLength base) {
           size_t depth = _stack.size() - 1;
           _index[depth].push_back(_pos - base);
diff --git a/3rdParty/velocypack/include/velocypack/Collection.h b/3rdParty/velocypack/include/velocypack/Collection.h
new file mode 100644
index 0000000000..8c690fc449
--- /dev/null
+++ b/3rdParty/velocypack/include/velocypack/Collection.h
@@ -0,0 +1,112 @@
+////////////////////////////////////////////////////////////////////////////////
+/// @brief Library to build up VPack documents.
+///
+/// DISCLAIMER
+///
+/// Copyright 2015 ArangoDB GmbH, Cologne, Germany
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///     http://www.apache.org/licenses/LICENSE-2.0
+///
+/// Unless required by applicable law or agreed to in writing, software
+/// distributed under the License is distributed on an "AS IS" BASIS,
+/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+/// See the License for the specific language governing permissions and
+/// limitations under the License.
+///
+/// Copyright holder is ArangoDB GmbH, Cologne, Germany
+///
+/// @author Max Neunhoeffer
+/// @author Jan Steemann
+/// @author Copyright 2015, ArangoDB GmbH, Cologne, Germany
+////////////////////////////////////////////////////////////////////////////////
+
+#ifndef VELOCYPACK_COLLECTION_H
+#define VELOCYPACK_COLLECTION_H 1
+
+#include <functional>
+#include <string>
+#include <unordered_set>
+#include <vector>
+
+#include "velocypack/velocypack-common.h"
+#include "velocypack/Builder.h"
+#include "velocypack/Slice.h"
+
+namespace arangodb {
+  namespace velocypack {
+
+    class Collection {
+
+      public:
+
+        Collection () = delete;
+
+        static void forEach (Slice const& slice, std::function<bool(Slice const&, ValueLength)> const& cb);
+        
+        static void forEach (Slice const* slice, std::function<bool(Slice const&, ValueLength)> const& cb) {
+          return forEach(*slice, cb);
+        }
+        
+        static Builder filter (Slice const& slice, std::function<bool(Slice const&, ValueLength)> const& cb);
+        
+        static Builder filter (Slice const* slice, std::function<bool(Slice const&, ValueLength)> const& cb) {
+          return filter(*slice, cb);
+        }
+        
+        static Builder map (Slice const& slice, std::function<Value(Slice const&, ValueLength)> const& cb);
+        
+        static Builder map (Slice const* slice, std::function<Value(Slice const&, ValueLength)> const& cb) {
+          return map(*slice, cb);
+        }
+        
+        static Slice find (Slice const& slice, std::function<bool(Slice const&, ValueLength)> const& cb);
+        
+        static Slice find (Slice const* slice, std::function<bool(Slice const&, ValueLength)> const& cb) {
+          return find(*slice, cb);
+        }
+        
+        static bool contains (Slice const& slice, std::function<bool(Slice const&, ValueLength)> const& cb);
+        
+        static bool contains (Slice const* slice, std::function<bool(Slice const&, ValueLength)> const& cb) {
+          return contains(*slice, cb);
+        }
+        
+        static bool all (Slice const& slice, std::function<bool(Slice const&, ValueLength)> const& cb);
+        
+        static bool all (Slice const* slice, std::function<bool(Slice const&, ValueLength)> const& cb) {
+          return all(*slice, cb);
+        }
+        
+        static bool any (Slice const& slice, std::function<bool(Slice const&, ValueLength)> const& cb);
+        
+        static bool any (Slice const* slice, std::function<bool(Slice const&, ValueLength)> const& cb) {
+          return any(*slice, cb);
+        }
+
+        static std::vector<std::string> keys (Slice const& slice);
+        
+        static std::vector<std::string> keys (Slice const* slice) {
+          return keys(*slice);
+        }
+        
+        static void keys (Slice const& slice, std::vector<std::string>& result);
+        
+        static void keys (Slice const* slice, std::vector<std::string>& result) {
+          return keys(*slice, result);
+        }
+        
+        static void keys (Slice const& slice, std::unordered_set<std::string>& result);
+        
+        static void keys (Slice const* slice, std::unordered_set<std::string>& result) {
+          return keys(*slice, result);
+        }
+    };
+
+  }  // namespace arangodb::velocypack
+}  // namespace arangodb
+
+#endif
diff --git a/3rdParty/velocypack/include/velocypack/Dumper.h b/3rdParty/velocypack/include/velocypack/Dumper.h
index 9817856f3e..0dd685204a 100644
--- a/3rdParty/velocypack/include/velocypack/Dumper.h
+++ b/3rdParty/velocypack/include/velocypack/Dumper.h
@@ -55,15 +55,15 @@ namespace arangodb {
         Options options;        
     
         enum UnsupportedTypeStrategy {
-          StrategyNullify,
-          StrategyFail
+          StrategyNullifyUnsupportedType,
+          StrategyFailOnUnsupportedType
         };
 
         Dumper (Dumper const&) = delete;
         Dumper& operator= (Dumper const&) = delete;
 
-        Dumper (T& buffer, UnsupportedTypeStrategy strategy = StrategyFail) 
-          : _buffer(&buffer), _strategy(strategy), _indentation(0) {
+        Dumper (T& buffer, UnsupportedTypeStrategy strategy = StrategyFailOnUnsupportedType) 
+          : strategy(strategy), _buffer(&buffer), _indentation(0) {
         }
 
         ~Dumper () {
@@ -99,24 +99,24 @@ namespace arangodb {
           internalDump(slice, nullptr);
         }
 
-        static void Dump (Slice const& slice, T& buffer, UnsupportedTypeStrategy strategy = StrategyFail) {
+        static void Dump (Slice const& slice, T& buffer, UnsupportedTypeStrategy strategy = StrategyFailOnUnsupportedType) {
           Dumper dumper(buffer, strategy);
           dumper.dump(slice);
         }
 
-        static void Dump (Slice const* slice, T& buffer, UnsupportedTypeStrategy strategy = StrategyFail) {
+        static void Dump (Slice const* slice, T& buffer, UnsupportedTypeStrategy strategy = StrategyFailOnUnsupportedType) {
           Dumper dumper(buffer, strategy);
           dumper.dump(slice);
         }
         
-        static T Dump (Slice const& slice, UnsupportedTypeStrategy strategy = StrategyFail) {
+        static T Dump (Slice const& slice, UnsupportedTypeStrategy strategy = StrategyFailOnUnsupportedType) {
           T buffer;
           Dumper dumper(buffer, strategy);
           dumper.dump(slice);
           return buffer;
         }
 
-        static T Dump (Slice const* slice, UnsupportedTypeStrategy strategy = StrategyFail) {
+        static T Dump (Slice const* slice, UnsupportedTypeStrategy strategy = StrategyFailOnUnsupportedType) {
           T buffer;
           Dumper dumper(buffer, strategy);
           dumper.dump(slice);
@@ -473,13 +473,16 @@ namespace arangodb {
         }
 
         void handleUnsupportedType (Slice const*) {
-          if (_strategy == StrategyNullify) {
+          if (strategy == StrategyNullifyUnsupportedType) {
             _buffer->append("null", 4);
             return;
           }
 
           throw Exception(Exception::NoJsonEquivalent);
         }
+        
+      public:
+        UnsupportedTypeStrategy strategy;
 
       private:
 
@@ -487,8 +490,6 @@ namespace arangodb {
           
         std::function<bool(T*, Slice const*, Slice const*)> _callback;
 
-        UnsupportedTypeStrategy _strategy;
-
         int _indentation;
 
     };
diff --git a/3rdParty/velocypack/include/velocypack/Exception.h b/3rdParty/velocypack/include/velocypack/Exception.h
index 982d447581..0b28929721 100644
--- a/3rdParty/velocypack/include/velocypack/Exception.h
+++ b/3rdParty/velocypack/include/velocypack/Exception.h
@@ -109,7 +109,7 @@ namespace arangodb {
             case BuilderObjectNotSealed:
               return "Object not sealed";
             case BuilderNeedOpenObject:
-              return "Need open array or object for close() call";
+              return "Need open Array or Object for close() call";
             case BuilderUnexpectedType:
               return "Unexpected type";
             case BuilderUnexpectedValue:
diff --git a/3rdParty/velocypack/include/velocypack/Iterator.h b/3rdParty/velocypack/include/velocypack/Iterator.h
new file mode 100644
index 0000000000..c3f883bd29
--- /dev/null
+++ b/3rdParty/velocypack/include/velocypack/Iterator.h
@@ -0,0 +1,144 @@
+////////////////////////////////////////////////////////////////////////////////
+/// @brief Library to build up VPack documents.
+///
+/// DISCLAIMER
+///
+/// Copyright 2015 ArangoDB GmbH, Cologne, Germany
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///     http://www.apache.org/licenses/LICENSE-2.0
+///
+/// Unless required by applicable law or agreed to in writing, software
+/// distributed under the License is distributed on an "AS IS" BASIS,
+/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+/// See the License for the specific language governing permissions and
+/// limitations under the License.
+///
+/// Copyright holder is ArangoDB GmbH, Cologne, Germany
+///
+/// @author Max Neunhoeffer
+/// @author Jan Steemann
+/// @author Copyright 2015, ArangoDB GmbH, Cologne, Germany
+////////////////////////////////////////////////////////////////////////////////
+
+#ifndef VELOCYPACK_ITERATOR_H
+#define VELOCYPACK_ITERATOR_H 1
+
+#include "velocypack/velocypack-common.h"
+#include "velocypack/Exception.h"
+#include "velocypack/Slice.h"
+#include "velocypack/ValueType.h"
+
+namespace arangodb {
+  namespace velocypack {
+
+    class ArrayIterator {
+
+      public:
+
+        ArrayIterator () = delete;
+
+        ArrayIterator (Slice const& slice) 
+          : _slice(slice), _size(_slice.length()), _position(0) {
+
+          if (slice.type() != ValueType::Array) {
+            throw Exception(Exception::InvalidValueType, "Expecting Array slice");
+          }
+        }
+        
+        ArrayIterator (ArrayIterator const& other) 
+          : _slice(other._slice), _size(other._size), _position(0) {
+        }
+        
+        ArrayIterator& operator= (ArrayIterator const& other) {
+          _slice = other._slice;
+          _size  = other._size;
+          _position = 0;
+          return *this;
+        }
+        
+        inline bool valid () const throw() {
+          return (_position < _size);
+        }
+
+        inline Slice value () const {
+          if (_position >= _size) {
+            throw Exception(Exception::IndexOutOfBounds);
+          }
+          return _slice.at(_position);
+        }
+
+        inline bool next () throw() {
+          ++_position;
+          return valid();
+        }
+
+      private: 
+
+        Slice _slice;
+        ValueLength _size;
+        ValueLength _position;
+    };
+    
+    class ObjectIterator {
+
+      public:
+
+        ObjectIterator () = delete;
+
+        ObjectIterator (Slice const& slice) 
+          : _slice(slice), _size(_slice.length()), _position(0) {
+
+          if (slice.type() != ValueType::Object) {
+            throw Exception(Exception::InvalidValueType, "Expecting Object slice");
+          }
+        }
+        
+        ObjectIterator (ObjectIterator const& other) 
+          : _slice(other._slice), _size(other._size), _position(0) {
+        }
+        
+        ObjectIterator& operator= (ObjectIterator const& other) {
+          _slice = other._slice;
+          _size  = other._size;
+          _position = 0;
+          return *this;
+        }
+        
+        inline bool valid () const throw() {
+          return (_position < _size);
+        }
+        
+        inline Slice key () const {
+          if (_position >= _size) {
+            throw Exception(Exception::IndexOutOfBounds);
+          }
+          return _slice.keyAt(_position);
+        }
+
+        inline Slice value () const {
+          if (_position >= _size) {
+            throw Exception(Exception::IndexOutOfBounds);
+          }
+          return _slice.valueAt(_position);
+        }
+
+        inline bool next () throw() {
+          ++_position;
+          return valid();
+        }
+
+      private: 
+
+        Slice _slice;
+        ValueLength _size;
+        ValueLength _position;
+    };
+
+  }  // namespace arangodb::velocypack
+}  // namespace arangodb
+
+#endif
diff --git a/3rdParty/velocypack/include/velocypack/Slice.h b/3rdParty/velocypack/include/velocypack/Slice.h
index fcfb2be152..4dfc467406 100644
--- a/3rdParty/velocypack/include/velocypack/Slice.h
+++ b/3rdParty/velocypack/include/velocypack/Slice.h
@@ -30,6 +30,7 @@
 #include <cstdint>
 #include <cstring>
 #include <string>
+#include <unordered_set>
 #include <vector>
 #include <ostream>
 #include <functional>
@@ -411,27 +412,6 @@ namespace arangodb {
           }
         }
         
-        std::vector<std::string> keys () const {
-          std::vector<std::string> keys;
-          ValueLength const n = length(); 
-          keys.reserve(n);
-          for (ValueLength i = 0; i < n; ++i) {
-            keys.emplace_back(keyAt(i).copyString());
-          }
-          return keys;
-        }
-
-        void keys (std::vector<std::string>& keys) const {
-          ValueLength const n = length(); 
-          if (! keys.empty()) {
-            keys.clear();
-          }
-          keys.reserve(n);
-          for (ValueLength i = 0; i < n; ++i) {
-            keys.emplace_back(keyAt(i).copyString());
-          }
-        }
-
         // return the pointer to the data for an External object
         char const* getExternal () const {
           return extractValue<char const*>();
diff --git a/3rdParty/velocypack/include/velocypack/Value.h b/3rdParty/velocypack/include/velocypack/Value.h
index dc23032d29..a55dd3863d 100644
--- a/3rdParty/velocypack/include/velocypack/Value.h
+++ b/3rdParty/velocypack/include/velocypack/Value.h
@@ -106,6 +106,21 @@ namespace arangodb {
           : _valueType(t), _cType(CType::UInt64) {
           _value.u = u;
         }
+#ifdef __APPLE__       
+        // MacOS uses the following typedefs:
+        // - typedef unsigned int         uint32_t;
+        // - typedef unsigned long long   uint64_t; 
+        // - typedef unsigned long        size_t;
+        // not defining the method for type unsigned long will prevent
+        // users from constructing Value objects with a size_t input
+
+        // however, defining the method on Linux and with MSVC will lead 
+        // to ambiguous overloads, so this is restricted to __APPLE__ only
+        explicit Value (unsigned long i, ValueType t = ValueType::Int)
+          : _valueType(t), _cType(CType::UInt64) {
+          _value.i = static_cast<uint64_t>(i);
+        }
+#endif        
         explicit Value (std::string const& s, ValueType t = ValueType::String)
           : _valueType(t), _cType(CType::String) {
           _value.s = &s;
diff --git a/3rdParty/velocypack/include/velocypack/ValueType.h b/3rdParty/velocypack/include/velocypack/ValueType.h
index 08948e6bba..f23a4dc118 100644
--- a/3rdParty/velocypack/include/velocypack/ValueType.h
+++ b/3rdParty/velocypack/include/velocypack/ValueType.h
@@ -27,6 +27,8 @@
 #ifndef VELOCYPACK_VALUETYPE_H
 #define VELOCYPACK_VALUETYPE_H
 
+#include <ostream>
+
 #include "velocypack-common.h"
 
 namespace arangodb {
@@ -57,4 +59,6 @@ namespace arangodb {
   }  // namespace arangodb::velocypack
 }  // namespace arangodb
 
+std::ostream& operator<< (std::ostream&, arangodb::velocypack::ValueType);
+
 #endif
diff --git a/3rdParty/velocypack/include/velocypack/velocypack-aliases.h b/3rdParty/velocypack/include/velocypack/velocypack-aliases.h
index 58ad2b03e1..7ed745bf8a 100644
--- a/3rdParty/velocypack/include/velocypack/velocypack-aliases.h
+++ b/3rdParty/velocypack/include/velocypack/velocypack-aliases.h
@@ -29,10 +29,13 @@
 
 #include "velocypack/vpack.h"
 
+using VPackArrayIterator      = arangodb::velocypack::ArrayIterator;
 using VPackBufferDumper       = arangodb::velocypack::BufferDumper;
 using VPackBuilder            = arangodb::velocypack::Builder;
 using VPackCharBuffer         = arangodb::velocypack::CharBuffer;
+using VPackCollection         = arangodb::velocypack::Collection;
 using VPackException          = arangodb::velocypack::Exception;
+using VPackObjectIterator     = arangodb::velocypack::ObjectIterator;
 using VPackOptions            = arangodb::velocypack::Options;
 using VPackParser             = arangodb::velocypack::Parser;
 using VPackStringDumper       = arangodb::velocypack::StringDumper;
diff --git a/3rdParty/velocypack/include/velocypack/vpack.h b/3rdParty/velocypack/include/velocypack/vpack.h
index c24297d704..1e1dcffac4 100644
--- a/3rdParty/velocypack/include/velocypack/vpack.h
+++ b/3rdParty/velocypack/include/velocypack/vpack.h
@@ -29,8 +29,10 @@
 
 #include "velocypack/velocypack-common.h"
 #include "velocypack/Builder.h"
+#include "velocypack/Collection.h"
 #include "velocypack/Dump.h"
 #include "velocypack/Exception.h"
+#include "velocypack/Iterator.h"
 #include "velocypack/Options.h"
 #include "velocypack/Parser.h"
 #include "velocypack/Slice.h"
diff --git a/3rdParty/velocypack/src/Builder.cpp b/3rdParty/velocypack/src/Builder.cpp
index 7ebb8e4e23..fcee680f14 100644
--- a/3rdParty/velocypack/src/Builder.cpp
+++ b/3rdParty/velocypack/src/Builder.cpp
@@ -295,7 +295,8 @@ void Builder::close () {
   // Intentionally leave _index[depth] intact to avoid future allocs!
 }
 
-void Builder::set (Value const& item) {
+uint8_t* Builder::set (Value const& item) {
+  auto const oldPos = _start + _pos;
   auto ctype = item.cType();
 
   // This method builds a single further VPack item at the current
@@ -521,6 +522,15 @@ void Builder::set (Value const& item) {
       throw Exception(Exception::BuilderUnexpectedType, "Cannot set a ValueType::Custom with this method");
     }
   }
+  return oldPos;
+}
+
+uint8_t* Builder::set (Slice const& item) {
+  ValueLength const l = item.byteSize();
+  reserveSpace(l);
+  memcpy(_start + _pos, item.start(), l);
+  _pos += l;
+  return _start + _pos - l;
 }
 
 uint8_t* Builder::set (ValuePair const& pair) {
@@ -615,80 +625,27 @@ void Builder::checkAttributeUniqueness (Slice const obj) const {
   }
 }
 
-void Builder::add (std::string const& attrName, Value const& sub) {
-  if (_attrWritten) {
-    throw Exception(Exception::InternalError, "Attribute name already written");
-  }
-  if (! _stack.empty()) {
-    ValueLength& tos = _stack.back();
-    if (_start[tos] != 0x06 &&
-        _start[tos] != 0x0b) {
-      throw Exception(Exception::BuilderNeedOpenObject);
-    }
-    reportAdd(tos);
-  }
-  set(Value(attrName, ValueType::String));
-  set(sub);
+uint8_t* Builder::add (std::string const& attrName, Value const& sub) {
+  return addInternal<Value>(attrName, sub);
+}
+
+uint8_t* Builder::add (std::string const& attrName, Slice const& sub) {
+  return addInternal<Slice>(attrName, sub);
 }
 
 uint8_t* Builder::add (std::string const& attrName, ValuePair const& sub) {
-  if (_attrWritten) {
-    throw Exception(Exception::InternalError, "Attribute name already written");
-  }
-  if (! _stack.empty()) {
-    ValueLength& tos = _stack.back();
-    if (_start[tos] != 0x06 &&
-        _start[tos] != 0x0b) {
-      throw Exception(Exception::BuilderNeedOpenObject);
-    }
-    reportAdd(tos);
-  }
-  set(Value(attrName, ValueType::String));
-  return set(sub);
+  return addInternal<ValuePair>(attrName, sub);
 }
 
-void Builder::add (Value const& sub) {
-  if (! _stack.empty()) {
-    ValueLength& tos = _stack.back();
-    if (_start[tos] != 0x06 && _start[tos] != 0x0b) {
-      // no array or object
-      throw Exception(Exception::BuilderNeedOpenObject);
-    }
-    if (_start[tos] == 0x0b) {   // object
-      if (! _attrWritten && ! sub.isString()) {
-        throw Exception(Exception::BuilderNeedOpenObject);
-      }
-      if (! _attrWritten) {
-        reportAdd(tos);
-      }
-      _attrWritten = ! _attrWritten;
-    }
-    else {
-      reportAdd(tos);
-    }
-  }
-  set(sub);
+uint8_t* Builder::add (Value const& sub) {
+  return addInternal<Value>(sub);
+}
+
+uint8_t* Builder::add (Slice const& sub) {
+  return addInternal<Slice>(sub);
 }
 
 uint8_t* Builder::add (ValuePair const& sub) {
-  if (! _stack.empty()) {
-    ValueLength& tos = _stack.back();
-    if (_start[tos] != 0x06 && _start[tos] != 0x0b) {
-      throw Exception(Exception::BuilderNeedOpenObject);
-    }
-    if (_start[tos] == 0x06) {   // object
-      if (! _attrWritten && ! sub.isString()) {
-        throw Exception(Exception::BuilderNeedOpenObject);
-      }
-      if (! _attrWritten) {
-        reportAdd(tos);
-      }
-      _attrWritten = ! _attrWritten;
-    }
-    else {
-      reportAdd(tos);
-    }
-  }
-  return set(sub);
+  return addInternal<ValuePair>(sub);
 }
 
diff --git a/3rdParty/velocypack/src/Collection.cpp b/3rdParty/velocypack/src/Collection.cpp
new file mode 100644
index 0000000000..3468a86f32
--- /dev/null
+++ b/3rdParty/velocypack/src/Collection.cpp
@@ -0,0 +1,179 @@
+////////////////////////////////////////////////////////////////////////////////
+/// @brief Library to build up VPack documents.
+///
+/// DISCLAIMER
+///
+/// Copyright 2015 ArangoDB GmbH, Cologne, Germany
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///     http://www.apache.org/licenses/LICENSE-2.0
+///
+/// Unless required by applicable law or agreed to in writing, software
+/// distributed under the License is distributed on an "AS IS" BASIS,
+/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+/// See the License for the specific language governing permissions and
+/// limitations under the License.
+///
+/// Copyright holder is ArangoDB GmbH, Cologne, Germany
+///
+/// @author Max Neunhoeffer
+/// @author Jan Steemann
+/// @author Copyright 2015, ArangoDB GmbH, Cologne, Germany
+////////////////////////////////////////////////////////////////////////////////
+
+#include "velocypack/velocypack-common.h"
+#include "velocypack/Collection.h"
+#include "velocypack/Iterator.h"
+#include "velocypack/Slice.h"
+#include "velocypack/Value.h"
+#include "velocypack/ValueType.h"
+
+using namespace arangodb::velocypack;
+
+void Collection::forEach (Slice const& slice, std::function<bool(Slice const&, ValueLength)> const& cb) {
+  ArrayIterator it(slice);
+  ValueLength index = 0;
+
+  while (it.valid()) {
+    if (! cb(it.value(), index)) {
+      // abort
+      return;
+    }
+    it.next();
+    ++index;
+  }
+}
+    
+Builder Collection::filter (Slice const& slice, std::function<bool(Slice const&, ValueLength)> const& cb) {
+  // construct a new Array
+  Builder b;
+  b.add(Value(ValueType::Array));
+
+  ArrayIterator it(slice);
+  ValueLength index = 0;
+
+  while (it.valid()) {
+    Slice s = it.value();
+    if (cb(s, index)) {
+      b.add(s);
+    }
+    it.next();
+    ++index;
+  }
+  b.close();
+  return b;
+}
+        
+Builder Collection::map (Slice const& slice, std::function<Value(Slice const&, ValueLength)> const& cb) {
+  // construct a new Array
+  Builder b;
+  b.add(Value(ValueType::Array));
+
+  ArrayIterator it(slice);
+  ValueLength index = 0;
+
+  while (it.valid()) {
+    b.add(cb(it.value(), index));
+    it.next();
+    ++index;
+  }
+  b.close();
+  return b;
+}
+
+Slice Collection::find (Slice const& slice, std::function<bool(Slice const&, ValueLength)> const& cb) {
+  ArrayIterator it(slice);
+  ValueLength index = 0;
+
+  while (it.valid()) {
+    Slice s = it.value();
+    if (cb(s, index)) {
+      return s;
+    }
+    it.next();
+    ++index;
+  }
+
+  return Slice();
+}
+        
+bool Collection::contains (Slice const& slice, std::function<bool(Slice const&, ValueLength)> const& cb) {
+  ArrayIterator it(slice);
+  ValueLength index = 0;
+
+  while (it.valid()) {
+    Slice s = it.value();
+    if (cb(s, index)) {
+      return true;
+    }
+    it.next();
+    ++index;
+  }
+
+  return false;
+}
+        
+bool Collection::all (Slice const& slice, std::function<bool(Slice const&, ValueLength)> const& cb) {
+  ArrayIterator it(slice);
+  ValueLength index = 0;
+
+  while (it.valid()) {
+    Slice s = it.value();
+    if (! cb(s, index)) {
+      return false;
+    }
+    it.next();
+    ++index;
+  }
+
+  return true;
+}
+        
+bool Collection::any (Slice const& slice, std::function<bool(Slice const&, ValueLength)> const& cb) {
+  ArrayIterator it(slice);
+  ValueLength index = 0;
+
+  while (it.valid()) {
+    Slice s = it.value();
+    if (cb(s, index)) {
+      return true;
+    }
+    it.next();
+    ++index;
+  }
+
+  return false;
+}
+        
+std::vector<std::string> Collection::keys (Slice const& slice) {
+  std::vector<std::string> result;
+
+  keys(slice, result);
+  
+  return result;
+}
+        
+void Collection::keys (Slice const& slice, std::vector<std::string>& result) {
+  // pre-allocate result vector
+  result.reserve(slice.length());
+
+  ObjectIterator it(slice);
+
+  while (it.valid()) {
+    result.emplace_back(it.key().copyString());
+    it.next();
+  }
+}
+        
+void Collection::keys (Slice const& slice, std::unordered_set<std::string>& result) {
+  ObjectIterator it(slice);
+
+  while (it.valid()) {
+    result.emplace(it.key().copyString());
+    it.next();
+  }
+}
+
diff --git a/3rdParty/velocypack/src/Slice.cpp b/3rdParty/velocypack/src/Slice.cpp
index d7739966c2..5f2f8ce110 100644
--- a/3rdParty/velocypack/src/Slice.cpp
+++ b/3rdParty/velocypack/src/Slice.cpp
@@ -25,6 +25,7 @@
 ////////////////////////////////////////////////////////////////////////////////
 
 #include "velocypack/velocypack-common.h"
+#include "velocypack/Builder.h"
 #include "velocypack/Dump.h"
 #include "velocypack/Slice.h"
 #include "velocypack/ValueType.h"
@@ -144,7 +145,7 @@ unsigned int const Slice::FirstSubMap[256] = {
   8,   // 0x12, object with unsorted index table
   0
 };
-
+        
 std::string Slice::toString () const {
   return StringPrettyDumper::Dump(this);
 }
diff --git a/3rdParty/velocypack/src/ValueType.cpp b/3rdParty/velocypack/src/ValueType.cpp
index c09986d08e..f0b68bc9ec 100644
--- a/3rdParty/velocypack/src/ValueType.cpp
+++ b/3rdParty/velocypack/src/ValueType.cpp
@@ -51,3 +51,8 @@ char const* arangodb::velocypack::ValueTypeName (ValueType type) {
 
   return "unknown";
 }
+
+std::ostream& operator<< (std::ostream& stream, ValueType type) {
+  stream << ValueTypeName(type);
+  return stream;
+}
diff --git a/lib/CMakeLists.txt b/lib/CMakeLists.txt
index 55bf5f927f..ab5e05ee98 100644
--- a/lib/CMakeLists.txt
+++ b/lib/CMakeLists.txt
@@ -53,6 +53,7 @@ include_directories(../3rdParty/velocypack/include)
 
 SET(LIB_ARANGO_VPACK
   ../3rdParty/velocypack/src/Builder.cpp
+  ../3rdParty/velocypack/src/Collection.cpp
   ../3rdParty/velocypack/src/Exception.cpp
   ../3rdParty/velocypack/src/Parser.cpp
   ../3rdParty/velocypack/src/Slice.cpp
diff --git a/lib/Makefile.files b/lib/Makefile.files
index b383087a61..28eaf2dde6 100644
--- a/lib/Makefile.files
+++ b/lib/Makefile.files
@@ -59,7 +59,7 @@ lib_libarango_a_SOURCES = \
 	lib/Basics/SpinLocker.cpp \
 	lib/Basics/ssl-helper.cpp \
 	lib/Basics/string-buffer.cpp \
-	lib/Basics/stringBufferAdapter.cpp \
+	lib/Basics/StringBufferAdapter.cpp \
 	lib/Basics/StringUtils.cpp \
 	lib/Basics/structures.cpp \
 	lib/Basics/system-functions.cpp \
@@ -110,6 +110,7 @@ endif
 
 lib_libarango_a_SOURCES += \
 	3rdParty/velocypack/src/Builder.cpp \
+	3rdParty/velocypack/src/Collection.cpp \
 	3rdParty/velocypack/src/Exception.cpp \
 	3rdParty/velocypack/src/Parser.cpp \
 	3rdParty/velocypack/src/Slice.cpp \