diff --git a/include/filter_result_iterator.h b/include/filter_result_iterator.h
index 143939ed..d288f32e 100644
--- a/include/filter_result_iterator.h
+++ b/include/filter_result_iterator.h
@@ -18,8 +18,9 @@ struct reference_filter_result_t {
     explicit reference_filter_result_t(uint32_t count = 0, uint32_t* docs = nullptr) : count(count), docs(docs) {}
 
     reference_filter_result_t(const reference_filter_result_t& obj) {
-        if (&obj == this)
+        if (&obj == this) {
             return;
+        }
 
         count = obj.count;
         docs = new uint32_t[count];
@@ -27,8 +28,9 @@ struct reference_filter_result_t {
     }
 
     reference_filter_result_t& operator=(const reference_filter_result_t& obj) noexcept {
-        if (&obj == this)
+        if (&obj == this) {
             return *this;
+        }
 
         count = obj.count;
         docs = new uint32_t[count];
@@ -38,8 +40,9 @@ struct reference_filter_result_t {
     }
 
     reference_filter_result_t& operator=(reference_filter_result_t&& obj) noexcept {
-        if (&obj == this)
+        if (&obj == this) {
             return *this;
+        }
 
         count = obj.count;
         docs = obj.docs;
@@ -65,8 +68,9 @@ struct single_filter_result_t {
                             seq_id(seq_id), reference_filter_results(std::move(reference_filter_results)) {}
 
     single_filter_result_t(const single_filter_result_t& obj) {
-        if (&obj == this)
+        if (&obj == this) {
             return;
+        }
 
         seq_id = obj.seq_id;
 
@@ -82,15 +86,16 @@ struct filter_result_t {
     uint32_t count = 0;
     uint32_t* docs = nullptr;
     // Collection name -> Reference filter result
-    std::unique_ptr<std::unique_ptr<std::map<std::string, reference_filter_result_t>> []> reference_filter_results;
+    std::map<std::string, reference_filter_result_t>* coll_to_references = nullptr;
 
     filter_result_t() = default;
 
     filter_result_t(uint32_t count, uint32_t* docs) : count(count), docs(docs) {}
 
     filter_result_t(const filter_result_t& obj) {
-        if (&obj == this)
+        if (&obj == this) {
             return;
+        }
 
         count = obj.count;
         docs = new uint32_t[count];
@@ -100,8 +105,9 @@ struct filter_result_t {
     }
 
     filter_result_t& operator=(const filter_result_t& obj) noexcept {
-        if (&obj == this)
+        if (&obj == this) {
             return *this;
+        }
 
         count = obj.count;
         docs = new uint32_t[count];
@@ -113,20 +119,23 @@ struct filter_result_t {
     }
 
     filter_result_t& operator=(filter_result_t&& obj) noexcept {
-        if (&obj == this)
+        if (&obj == this) {
             return *this;
+        }
 
         count = obj.count;
         docs = obj.docs;
-        reference_filter_results = std::move(obj.reference_filter_results);
+        coll_to_references = obj.coll_to_references;
 
         obj.docs = nullptr;
+        obj.coll_to_references = nullptr;
 
         return *this;
     }
 
     ~filter_result_t() {
         delete[] docs;
+        delete[] coll_to_references;
     }
 
     static void and_filter_results(const filter_result_t& a, const filter_result_t& b, filter_result_t& result);
diff --git a/src/filter_result_iterator.cpp b/src/filter_result_iterator.cpp
index 5d226673..7f4a45b9 100644
--- a/src/filter_result_iterator.cpp
+++ b/src/filter_result_iterator.cpp
@@ -14,20 +14,19 @@
 #include "collection_manager.h"
 
 void filter_result_t::copy_references(const filter_result_t& from, filter_result_t& to) {
-    if (from.reference_filter_results == nullptr) {
+    if (from.coll_to_references == nullptr) {
         return;
     }
 
     auto const& count = from.count;
-    to.reference_filter_results = std::make_unique<std::unique_ptr<std::map<std::string, reference_filter_result_t>> []>(count);
+    to.coll_to_references = new std::map<std::string, reference_filter_result_t>[count] {};
     for (uint32_t i = 0; i < count; i++) {
-        if (from.reference_filter_results[i] == nullptr) {
+        if (from.coll_to_references[i].empty()) {
             continue;
         }
 
-        auto& ref = to.reference_filter_results[i];
-        ref = std::make_unique<std::map<std::string, reference_filter_result_t>>();
-        ref->insert(from.reference_filter_results[i]->begin(), from.reference_filter_results[i]->end());
+        auto& ref = to.coll_to_references[i];
+        ref.insert(from.coll_to_references[i].begin(), from.coll_to_references[i].end());
     }
 }
 
@@ -43,8 +42,8 @@ void filter_result_t::and_filter_results(const filter_result_t& a, const filter_
     const uint32_t *endA = A + lenA;
     const uint32_t *endB = B + lenB;
 
-    if (a.reference_filter_results != nullptr || b.reference_filter_results != nullptr) {
-        result.reference_filter_results = std::make_unique<std::unique_ptr<std::map<std::string, reference_filter_result_t>> []>(std::min(lenA, lenB));
+    if (a.coll_to_references != nullptr || b.coll_to_references != nullptr) {
+        result.coll_to_references = new std::map<std::string, reference_filter_result_t>[std::min(lenA, lenB)] {};
     }
 
     while (true) {
@@ -64,17 +63,14 @@ void filter_result_t::and_filter_results(const filter_result_t& a, const filter_
         if (*A == *B) {
             *out = *A;
 
-            if (result.reference_filter_results != nullptr) {
+            if (result.coll_to_references != nullptr) {
                 // Copy the references of the document from every collection into result.
-                auto& ref = result.reference_filter_results[out - result.docs];
-                ref = std::make_unique<std::map<std::string, reference_filter_result_t>>();
-                if (a.reference_filter_results != nullptr && a.reference_filter_results[A - a.docs] != nullptr) {
-                    ref->insert(a.reference_filter_results[A - a.docs]->begin(),
-                                a.reference_filter_results[A - a.docs]->end());
+                auto& ref = result.coll_to_references[out - result.docs];
+                if (a.coll_to_references != nullptr) {
+                    ref.insert(a.coll_to_references[A - a.docs].begin(), a.coll_to_references[A - a.docs].end());
                 }
-                if (b.reference_filter_results != nullptr && b.reference_filter_results[B - b.docs] != nullptr) {
-                    ref->insert(b.reference_filter_results[B - b.docs]->begin(),
-                                b.reference_filter_results[B - b.docs]->end());
+                if (b.coll_to_references != nullptr) {
+                    ref.insert(b.coll_to_references[B - b.docs].begin(), b.coll_to_references[B - b.docs].end());
                 }
             }
 
@@ -108,8 +104,8 @@ void filter_result_t::or_filter_results(const filter_result_t& a, const filter_r
     size_t indexA = 0, indexB = 0, res_index = 0, lenA = a.count, lenB = b.count;
     result.docs = new uint32_t[lenA + lenB];
 
-    if (a.reference_filter_results != nullptr || b.reference_filter_results != nullptr) {
-        result.reference_filter_results = std::make_unique<std::unique_ptr<std::map<std::string, reference_filter_result_t>> []>(lenA + lenB);
+    if (a.coll_to_references != nullptr || b.coll_to_references != nullptr) {
+        result.coll_to_references = new std::map<std::string, reference_filter_result_t>[lenA + lenB] {};
     }
 
     while (indexA < lenA && indexB < lenB) {
@@ -120,13 +116,10 @@ void filter_result_t::or_filter_results(const filter_result_t& a, const filter_r
                 res_index++;
             }
 
-            if (a.reference_filter_results != nullptr && a.reference_filter_results[indexA] != nullptr) {
+            if (a.coll_to_references != nullptr) {
                 // Copy references of the last result document from every collection in a.
-                auto &ref = result.reference_filter_results[res_index - 1];
-                if (ref == nullptr) {
-                    ref = std::make_unique<std::map<std::string, reference_filter_result_t>>();
-                }
-                ref->insert(a.reference_filter_results[indexA]->begin(), a.reference_filter_results[indexA]->end());
+                auto &ref = result.coll_to_references[res_index - 1];
+                ref.insert(a.coll_to_references[indexA].begin(), a.coll_to_references[indexA].end());
             }
 
             indexA++;
@@ -136,12 +129,9 @@ void filter_result_t::or_filter_results(const filter_result_t& a, const filter_r
                 res_index++;
             }
 
-            if (b.reference_filter_results != nullptr && b.reference_filter_results[indexB] != nullptr) {
-                auto &ref = result.reference_filter_results[res_index - 1];
-                if (ref == nullptr) {
-                    ref = std::make_unique<std::map<std::string, reference_filter_result_t>>();
-                }
-                ref->insert(b.reference_filter_results[indexB]->begin(), b.reference_filter_results[indexB]->end());
+            if (b.coll_to_references != nullptr) {
+                auto &ref = result.coll_to_references[res_index - 1];
+                ref.insert(b.coll_to_references[indexB].begin(), b.coll_to_references[indexB].end());
             }
 
             indexB++;
@@ -154,12 +144,9 @@ void filter_result_t::or_filter_results(const filter_result_t& a, const filter_r
             res_index++;
         }
 
-        if (a.reference_filter_results != nullptr && a.reference_filter_results[indexA] != nullptr) {
-            auto &ref = result.reference_filter_results[res_index - 1];
-            if (ref == nullptr) {
-                ref = std::make_unique<std::map<std::string, reference_filter_result_t>>();
-            }
-            ref->insert(a.reference_filter_results[indexA]->begin(), a.reference_filter_results[indexA]->end());
+        if (a.coll_to_references != nullptr) {
+            auto &ref = result.coll_to_references[res_index - 1];
+            ref.insert(a.coll_to_references[indexA].begin(), a.coll_to_references[indexA].end());
         }
 
         indexA++;
@@ -171,12 +158,9 @@ void filter_result_t::or_filter_results(const filter_result_t& a, const filter_r
             res_index++;
         }
 
-        if (b.reference_filter_results != nullptr && b.reference_filter_results[indexB] != nullptr) {
-            auto &ref = result.reference_filter_results[res_index - 1];
-            if (ref == nullptr) {
-                ref = std::make_unique<std::map<std::string, reference_filter_result_t>>();
-            }
-            ref->insert(b.reference_filter_results[indexB]->begin(), b.reference_filter_results[indexB]->end());
+        if (b.coll_to_references != nullptr) {
+            auto &ref = result.coll_to_references[res_index - 1];
+            ref.insert(b.coll_to_references[indexB].begin(), b.coll_to_references[indexB].end());
         }
 
         indexB++;
@@ -194,22 +178,17 @@ void filter_result_t::or_filter_results(const filter_result_t& a, const filter_r
     delete[] result.docs;
     result.docs = out;
 
-    if (result.reference_filter_results == nullptr) {
+    if (result.coll_to_references == nullptr) {
         return;
     }
 
-    auto out_references = std::make_unique<std::unique_ptr<std::map<std::string, reference_filter_result_t>> []>(res_index);
+    auto out_references = new std::map<std::string, reference_filter_result_t>[res_index] {};
     for (uint32_t i = 0; i < res_index; i++) {
-        if (result.reference_filter_results[i] == nullptr) {
-            continue;
-        }
-
         auto& ref = out_references[i];
-        ref = std::make_unique<std::map<std::string, reference_filter_result_t>>();
-        ref->insert(result.reference_filter_results[i]->begin(), result.reference_filter_results[i]->end());
+        ref.insert(result.coll_to_references[i].begin(), result.coll_to_references[i].end());
     }
 
-    result.reference_filter_results = std::move(out_references);
+    result.coll_to_references = out_references;
 }
 
 void filter_result_iterator_t::and_filter_iterators() {
@@ -445,9 +424,8 @@ void filter_result_iterator_t::next() {
 
         seq_id = filter_result.docs[result_index];
         reference.clear();
-        if (filter_result.reference_filter_results != nullptr &&
-            filter_result.reference_filter_results[result_index] != nullptr) {
-            auto& ref = *filter_result.reference_filter_results[result_index];
+        if (filter_result.coll_to_references != nullptr) {
+            auto& ref = filter_result.coll_to_references[result_index];
             reference.insert(ref.begin(), ref.end());
         }
 
@@ -703,9 +681,8 @@ void filter_result_iterator_t::init() {
         }
 
         seq_id = filter_result.docs[result_index];
-        if (filter_result.reference_filter_results != nullptr &&
-            filter_result.reference_filter_results[result_index] != nullptr) {
-            auto& ref = *filter_result.reference_filter_results[result_index];
+        if (filter_result.coll_to_references != nullptr) {
+            auto& ref = filter_result.coll_to_references[result_index];
             reference.insert(ref.begin(), ref.end());
         }
 
@@ -1180,9 +1157,8 @@ void filter_result_iterator_t::skip_to(uint32_t id) {
 
         seq_id = filter_result.docs[result_index];
         reference.clear();
-        if (filter_result.reference_filter_results != nullptr &&
-            filter_result.reference_filter_results[result_index] != nullptr) {
-            auto& ref = *filter_result.reference_filter_results[result_index];
+        if (filter_result.coll_to_references != nullptr) {
+            auto& ref = filter_result.coll_to_references[result_index];
             reference.insert(ref.begin(), ref.end());
         }
 
@@ -1415,9 +1391,8 @@ void filter_result_iterator_t::reset() {
         seq_id = filter_result.docs[result_index];
 
         reference.clear();
-        if (filter_result.reference_filter_results != nullptr &&
-            filter_result.reference_filter_results[result_index] != nullptr) {
-            auto& ref = *filter_result.reference_filter_results[result_index];
+        if (filter_result.coll_to_references != nullptr) {
+            auto& ref = filter_result.coll_to_references[result_index];
             reference.insert(ref.begin(), ref.end());
         }
 
@@ -1523,7 +1498,7 @@ void filter_result_iterator_t::and_scalar(const uint32_t* A, const uint32_t& len
         return;
     }
 
-    if (filter_result.reference_filter_results == nullptr) {
+    if (filter_result.coll_to_references == nullptr) {
         if (is_filter_result_initialized) {
             result.count = ArrayUtils::and_scalar(A, lenA, filter_result.docs, filter_result.count, &result.docs);
             return;
@@ -1571,20 +1546,15 @@ void filter_result_iterator_t::and_scalar(const uint32_t* A, const uint32_t& len
 
     result.count = match_indexes.size();
     result.docs = new uint32_t[match_indexes.size()];
-    result.reference_filter_results = std::make_unique<std::unique_ptr<std::map<std::string, reference_filter_result_t>> []>(match_indexes.size());
+    result.coll_to_references = new std::map<std::string, reference_filter_result_t>[match_indexes.size()] {};
 
     for (uint32_t i = 0; i < match_indexes.size(); i++) {
         auto const& match_index = match_indexes[i];
         result.docs[i] = filter_result.docs[match_index];
 
-        if (filter_result.reference_filter_results[match_index] == nullptr) {
-            continue;
-        }
-
-        auto& result_reference = result.reference_filter_results[i];
-        result_reference = std::make_unique<std::map<std::string, reference_filter_result_t>>();
-        result_reference->insert(filter_result.reference_filter_results[match_index]->begin(),
-                                 filter_result.reference_filter_results[match_index]->end());
+        auto& result_reference = result.coll_to_references[i];
+        result_reference.insert(filter_result.coll_to_references[match_index].begin(),
+                                 filter_result.coll_to_references[match_index].end());
     }
 }
 
@@ -1672,21 +1642,21 @@ void filter_result_iterator_t::get_n_ids(const uint32_t& n, filter_result_t*& re
 
     auto result_length = result->count = std::min(n, filter_result.count - result_index);
     result->docs = new uint32_t[result_length];
-    if (filter_result.reference_filter_results != nullptr) {
-        result->reference_filter_results = std::make_unique<std::unique_ptr<std::map<std::string, reference_filter_result_t>>[]>(result_length);
+    if (filter_result.coll_to_references != nullptr) {
+        result->coll_to_references = new std::map<std::string, reference_filter_result_t>[result_length] {};
     }
 
     for (uint32_t i = 0; i < result_length; i++, result_index++) {
         result->docs[i] = filter_result.docs[result_index];
 
-        if (filter_result.reference_filter_results == nullptr) {
+        if (filter_result.coll_to_references == nullptr) {
             continue;
         }
 
-        auto& result_reference = result->reference_filter_results[i];
+        auto& result_reference = result->coll_to_references[i];
         // Moving references since get_n_ids is only called in wildcard search flow and filter_result_iterator is
         // not used afterwards.
-        result_reference = std::move(filter_result.reference_filter_results[result_index]);
+        result_reference = std::move(filter_result.coll_to_references[result_index]);
     }
 
     is_valid = result_index < filter_result.count;
@@ -1718,22 +1688,22 @@ void filter_result_iterator_t::get_n_ids(const uint32_t& n,
 
     result->count = match_indexes.size();
     result->docs = new uint32_t[match_indexes.size()];
-    if (filter_result.reference_filter_results != nullptr) {
-        result->reference_filter_results = std::make_unique<std::unique_ptr<std::map<std::string, reference_filter_result_t>>[]>(match_indexes.size());
+    if (filter_result.coll_to_references != nullptr) {
+        result->coll_to_references = new std::map<std::string, reference_filter_result_t>[match_indexes.size()] {};
     }
 
     for (uint32_t i = 0; i < match_indexes.size(); i++) {
         auto const& match_index = match_indexes[i];
         result->docs[i] = filter_result.docs[match_index];
 
-        if (filter_result.reference_filter_results == nullptr) {
+        if (filter_result.coll_to_references == nullptr) {
             continue;
         }
 
-        auto& result_reference = result->reference_filter_results[i];
+        auto& result_reference = result->coll_to_references[i];
         // Moving references since get_n_ids is only called in wildcard search flow and filter_result_iterator is
         // not used afterwards.
-        result_reference = std::move(filter_result.reference_filter_results[match_index]);
+        result_reference = std::move(filter_result.coll_to_references[match_index]);
     }
 
     is_valid = result_index < filter_result.count;
diff --git a/src/index.cpp b/src/index.cpp
index f6ed5ed9..1d879bbd 100644
--- a/src/index.cpp
+++ b/src/index.cpp
@@ -1732,18 +1732,17 @@ Option<bool> Index::do_reference_filtering_with_lock(filter_node_t* const filter
 
     filter_result.count = result.size();
     filter_result.docs = new uint32_t[result.size()];
-    filter_result.reference_filter_results = std::make_unique<std::unique_ptr<std::map<std::string, reference_filter_result_t>> []>(result.size());
+    filter_result.coll_to_references = new std::map<std::string, reference_filter_result_t>[result.size()] {};
 
     for (uint32_t result_index = 0; result_index < result.size(); result_index++) {
         filter_result.docs[result_index] = result[result_index].first;
 
-        auto& reference_result = filter_result.reference_filter_results[result_index];
-        reference_result = std::make_unique<std::map<std::string, reference_filter_result_t>>();
+        auto& reference_result = filter_result.coll_to_references[result_index];
 
         auto const& references = result[result_index].second;
         auto r = reference_filter_result_t(references.size(), new uint32_t[references.size()]);
         std::copy(references.begin(), references.end(), r.docs);
-        (*reference_result)[collection_name] = std::move(r);
+        reference_result[collection_name] = std::move(r);
     }
 
     return Option(true);
@@ -4707,9 +4706,8 @@ Option<bool> Index::do_infix_search(const size_t num_search_fields, const std::v
                 for(size_t i = 0; i < raw_infix_ids_length; i++) {
                     auto seq_id = raw_infix_ids[i];
                     std::map<std::string, reference_filter_result_t> references;
-                    if (filtered_infix_ids.reference_filter_results != nullptr &&
-                        filtered_infix_ids.reference_filter_results[i] != nullptr) {
-                        references = std::move(*filtered_infix_ids.reference_filter_results[i]);
+                    if (filtered_infix_ids.coll_to_references != nullptr) {
+                        references = std::move(filtered_infix_ids.coll_to_references[i]);
                     }
 
                     int64_t match_score = 0;
@@ -5093,9 +5091,8 @@ Option<bool> Index::search_wildcard(filter_node_t const* const& filter_tree_root
             for(size_t i = 0; i < batch_result->count; i++) {
                 const uint32_t seq_id = batch_result->docs[i];
                 std::map<basic_string<char>, reference_filter_result_t> references;
-                if (batch_result->reference_filter_results != nullptr &&
-                    batch_result->reference_filter_results[i] != nullptr) {
-                    references = std::move(*batch_result->reference_filter_results[i]);
+                if (batch_result->coll_to_references != nullptr) {
+                    references = std::move(batch_result->coll_to_references[i]);
                 }
 
                 int64_t match_score = 0;
diff --git a/test/collection_join_test.cpp b/test/collection_join_test.cpp
index fed20f59..495f9ba4 100644
--- a/test/collection_join_test.cpp
+++ b/test/collection_join_test.cpp
@@ -651,7 +651,7 @@ TEST_F(CollectionJoinTest, AndFilterResults_NoReference) {
     filter_result_t::and_filter_results(a, b, result);
 
     ASSERT_EQ(2, result.count);
-    ASSERT_EQ(nullptr, result.reference_filter_results);
+    ASSERT_EQ(nullptr, result.coll_to_references);
 
     std::vector<uint32_t> docs = {3, 6};
 
@@ -664,31 +664,31 @@ TEST_F(CollectionJoinTest, AndFilterResults_WithReferences) {
     filter_result_t a;
     a.count = 9;
     a.docs = new uint32_t[a.count];
-    a.reference_filter_results = std::make_unique<std::unique_ptr<std::map<std::string, reference_filter_result_t>> []>(a.count);
+    a.coll_to_references = new std::map<std::string, reference_filter_result_t>[a.count] {};
 
     for (size_t i = 0; i < a.count; i++) {
         a.docs[i] = i;
 
-        auto& reference = a.reference_filter_results[i] = std::make_unique<std::map<std::string, reference_filter_result_t>>();
+        auto& reference = a.coll_to_references[i];
         // Having only one reference of each document for brevity.
         auto reference_docs = new uint32_t[1];
         reference_docs[0] = 10 - i;
-        (*reference)["foo"] = reference_filter_result_t(1, reference_docs);
+        reference["foo"] = reference_filter_result_t(1, reference_docs);
     }
 
     filter_result_t b;
     b.count = 0;
     uint32_t limit = 10;
     b.docs = new uint32_t[limit];
-    b.reference_filter_results = std::make_unique<std::unique_ptr<std::map<std::string, reference_filter_result_t>> []>(limit);
+    b.coll_to_references = new std::map<std::string, reference_filter_result_t>[limit] {};
     for (size_t i = 2; i < limit; i++) {
         if (i % 3 == 0) {
             b.docs[b.count] = i;
 
-            auto& reference = b.reference_filter_results[b.count++] = std::make_unique<std::map<std::string, reference_filter_result_t>>();
+            auto& reference = b.coll_to_references[b.count++];
             auto reference_docs = new uint32_t[1];
             reference_docs[0] = 2 * i;
-            (*reference)["bar"] = reference_filter_result_t(1, reference_docs);
+            reference["bar"] = reference_filter_result_t(1, reference_docs);
         }
     }
 
@@ -697,9 +697,9 @@ TEST_F(CollectionJoinTest, AndFilterResults_WithReferences) {
     filter_result_t::and_filter_results(a, b, result);
 
     ASSERT_EQ(2, result.count);
-    ASSERT_EQ(2, result.reference_filter_results[0]->size());
-    ASSERT_EQ(1, result.reference_filter_results[0]->count("foo"));
-    ASSERT_EQ(1, result.reference_filter_results[0]->count("bar"));
+    ASSERT_EQ(2, result.coll_to_references[0].size());
+    ASSERT_EQ(1, result.coll_to_references[0].count("foo"));
+    ASSERT_EQ(1, result.coll_to_references[0].count("bar"));
 
     std::vector<uint32_t> docs = {3, 6}, foo_reference = {7, 4}, bar_reference = {6, 12};
 
@@ -707,10 +707,10 @@ TEST_F(CollectionJoinTest, AndFilterResults_WithReferences) {
         ASSERT_EQ(docs[i], result.docs[i]);
 
         // result should contain correct references to the foo and bar collection.
-        ASSERT_EQ(1, result.reference_filter_results[i]->at("foo").count);
-        ASSERT_EQ(foo_reference[i], result.reference_filter_results[i]->at("foo").docs[0]);
-        ASSERT_EQ(1, result.reference_filter_results[i]->at("bar").count);
-        ASSERT_EQ(bar_reference[i], result.reference_filter_results[i]->at("bar").docs[0]);
+        ASSERT_EQ(1, result.coll_to_references[i].at("foo").count);
+        ASSERT_EQ(foo_reference[i], result.coll_to_references[i].at("foo").docs[0]);
+        ASSERT_EQ(1, result.coll_to_references[i].at("bar").count);
+        ASSERT_EQ(bar_reference[i], result.coll_to_references[i].at("bar").docs[0]);
     }
 }
 
@@ -729,7 +729,7 @@ TEST_F(CollectionJoinTest, OrFilterResults_NoReference) {
     filter_result_t result1;
     filter_result_t::or_filter_results(a, b, result1);
     ASSERT_EQ(3, result1.count);
-    ASSERT_EQ(nullptr, result1.reference_filter_results);
+    ASSERT_EQ(nullptr, result1.coll_to_references);
 
     std::vector<uint32_t> expected = {3, 6, 9};
     for (size_t i = 0; i < result1.count; i++) {
@@ -746,7 +746,7 @@ TEST_F(CollectionJoinTest, OrFilterResults_NoReference) {
     filter_result_t result2;
     filter_result_t::or_filter_results(a, b, result2);
     ASSERT_EQ(10, result2.count);
-    ASSERT_EQ(nullptr, result2.reference_filter_results);
+    ASSERT_EQ(nullptr, result2.coll_to_references);
 
     expected = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
     for (size_t i = 0; i < result2.count; i++) {
@@ -766,7 +766,7 @@ TEST_F(CollectionJoinTest, OrFilterResults_NoReference) {
     // b.docs: [0..8], c.docs: [0, 4, 5]
     filter_result_t::or_filter_results(b, c, result3);
     ASSERT_EQ(9, result3.count);
-    ASSERT_EQ(nullptr, result3.reference_filter_results);
+    ASSERT_EQ(nullptr, result3.coll_to_references);
 
     expected = {0, 1, 2, 3, 4, 5, 6, 7, 8};
     for(size_t i = 0; i < result3.count; i++) {
@@ -780,15 +780,15 @@ TEST_F(CollectionJoinTest, OrFilterResults_WithReferences) {
 
     a.count = 0;
     a.docs = new uint32_t[limit];
-    a.reference_filter_results = std::make_unique<std::unique_ptr<std::map<std::string, reference_filter_result_t>> []>(limit);
+    a.coll_to_references = new std::map<std::string, reference_filter_result_t>[limit] {};
     for (size_t i = 2; i < limit; i++) {
         if (i % 3 == 0) {
             a.docs[a.count] = i;
 
-            auto& reference = a.reference_filter_results[a.count++] = std::make_unique<std::map<std::string, reference_filter_result_t>>();
+            auto& reference = a.coll_to_references[a.count++];
             auto reference_docs = new uint32_t[1];
             reference_docs[0] = 2 * i;
-            (*reference)["foo"] = reference_filter_result_t(1, reference_docs);
+            reference["foo"] = reference_filter_result_t(1, reference_docs);
         }
     }
 
@@ -797,27 +797,27 @@ TEST_F(CollectionJoinTest, OrFilterResults_WithReferences) {
     filter_result_t::or_filter_results(a, b, result1);
 
     ASSERT_EQ(3, result1.count);
-    ASSERT_EQ(1, result1.reference_filter_results[0]->size());
-    ASSERT_EQ(1, result1.reference_filter_results[0]->count("foo"));
+    ASSERT_EQ(1, result1.coll_to_references[0].size());
+    ASSERT_EQ(1, result1.coll_to_references[0].count("foo"));
 
     std::vector<uint32_t> expected = {3, 6, 9}, foo_reference = {6, 12, 18};
     for (size_t i = 0; i < result1.count; i++) {
         ASSERT_EQ(expected[i], result1.docs[i]);
 
-        ASSERT_EQ(1, result1.reference_filter_results[i]->at("foo").count);
-        ASSERT_EQ(foo_reference[i], result1.reference_filter_results[i]->at("foo").docs[0]);
+        ASSERT_EQ(1, result1.coll_to_references[i].at("foo").count);
+        ASSERT_EQ(foo_reference[i], result1.coll_to_references[i].at("foo").docs[0]);
     }
 
     b.count = 9;
     b.docs = new uint32_t[b.count];
-    b.reference_filter_results = std::make_unique<std::unique_ptr<std::map<std::string, reference_filter_result_t>> []>(b.count);
+    b.coll_to_references = new std::map<std::string, reference_filter_result_t>[b.count] {};
     for (size_t i = 0; i < b.count; i++) {
         b.docs[i] = i;
 
-        auto& reference = b.reference_filter_results[i] = std::make_unique<std::map<std::string, reference_filter_result_t>>();
+        auto& reference = b.coll_to_references[i];
         auto reference_docs = new uint32_t[1];
         reference_docs[0] = 10 - i;
-        (*reference)["bar"] = reference_filter_result_t(1, reference_docs);
+        reference["bar"] = reference_filter_result_t(1, reference_docs);
     }
 
     // a.docs: [3, 6, 9], b.docs: [0..8]
@@ -834,18 +834,18 @@ TEST_F(CollectionJoinTest, OrFilterResults_WithReferences) {
         ASSERT_EQ(expected[i], result2.docs[i]);
 
         if (foo_map.count(i) != 0) {
-            ASSERT_EQ(1, result2.reference_filter_results[i]->at("foo").count);
-            ASSERT_EQ(foo_map[i], result2.reference_filter_results[i]->at("foo").docs[0]);
+            ASSERT_EQ(1, result2.coll_to_references[i].at("foo").count);
+            ASSERT_EQ(foo_map[i], result2.coll_to_references[i].at("foo").docs[0]);
         } else {
             // foo didn't have any reference to current doc.
-            ASSERT_EQ(0, result2.reference_filter_results[i]->count("foo"));
+            ASSERT_EQ(0, result2.coll_to_references[i].count("foo"));
         }
 
         if (bar_map.count(i) != 0) {
-            ASSERT_EQ(1, result2.reference_filter_results[i]->at("bar").count);
-            ASSERT_EQ(bar_map[i], result2.reference_filter_results[i]->at("bar").docs[0]);
+            ASSERT_EQ(1, result2.coll_to_references[i].at("bar").count);
+            ASSERT_EQ(bar_map[i], result2.coll_to_references[i].at("bar").docs[0]);
         } else {
-            ASSERT_EQ(0, result2.reference_filter_results[i]->count("bar"));
+            ASSERT_EQ(0, result2.coll_to_references[i].count("bar"));
         }
     }
 
@@ -854,15 +854,15 @@ TEST_F(CollectionJoinTest, OrFilterResults_WithReferences) {
     std::map<uint32_t, uint32_t> baz_map = {{0, 2}, {4, 0}, {5, 8}};
     c.count = baz_map.size();
     c.docs = new uint32_t[baz_map.size()];
-    c.reference_filter_results = std::make_unique<std::unique_ptr<std::map<std::string, reference_filter_result_t>> []>(baz_map.size());
+    c.coll_to_references = new std::map<std::string, reference_filter_result_t>[baz_map.size()] {};
     auto j = 0;
     for(auto i: baz_map) {
         c.docs[j] = i.first;
 
-        auto& reference = c.reference_filter_results[j++] = std::make_unique<std::map<std::string, reference_filter_result_t>>();
+        auto& reference = c.coll_to_references[j++];
         auto reference_docs = new uint32_t[1];
         reference_docs[0] = i.second;
-        (*reference)["baz"] = reference_filter_result_t(1, reference_docs);
+        reference["baz"] = reference_filter_result_t(1, reference_docs);
     }
 
     // b.docs: [0..8], c.docs: [0, 4, 5]
@@ -874,17 +874,17 @@ TEST_F(CollectionJoinTest, OrFilterResults_WithReferences) {
         ASSERT_EQ(expected[i], result3.docs[i]);
 
         if (bar_map.count(i) != 0) {
-            ASSERT_EQ(1, result3.reference_filter_results[i]->at("bar").count);
-            ASSERT_EQ(bar_map[i], result3.reference_filter_results[i]->at("bar").docs[0]);
+            ASSERT_EQ(1, result3.coll_to_references[i].at("bar").count);
+            ASSERT_EQ(bar_map[i], result3.coll_to_references[i].at("bar").docs[0]);
         } else {
-            ASSERT_EQ(0, result3.reference_filter_results[i]->count("bar"));
+            ASSERT_EQ(0, result3.coll_to_references[i].count("bar"));
         }
 
         if (baz_map.count(i) != 0) {
-            ASSERT_EQ(1, result3.reference_filter_results[i]->at("baz").count);
-            ASSERT_EQ(baz_map[i], result3.reference_filter_results[i]->at("baz").docs[0]);
+            ASSERT_EQ(1, result3.coll_to_references[i].at("baz").count);
+            ASSERT_EQ(baz_map[i], result3.coll_to_references[i].at("baz").docs[0]);
         } else {
-            ASSERT_EQ(0, result3.reference_filter_results[i]->count("baz"));
+            ASSERT_EQ(0, result3.coll_to_references[i].count("baz"));
         }
     }
 }