diff --git a/external/bits b/external/bits
index 63ef155..f5498a8 160000
--- a/external/bits
+++ b/external/bits
@@ -1 +1 @@
-Subproject commit 63ef155259d823976ff3bad3f803afba5ab4573f
+Subproject commit f5498a856f13e657d62c78afa22448c16d335972
diff --git a/include/partitioned_phf.hpp b/include/partitioned_phf.hpp
index 8426e3d..ff5e251 100644
--- a/include/partitioned_phf.hpp
+++ b/include/partitioned_phf.hpp
@@ -94,7 +94,8 @@ struct partitioned_phf  //
         m_num_keys = builder.num_keys();
         m_table_size = builder.table_size();
         m_partitioner = builder.bucketer();
-        m_partitions.resize(num_partitions);
+        std::vector<partition> partitions;
+        partitions.resize(num_partitions);
 
         auto const& offsets = builder.offsets();
         auto const& builders = builder.builders();
@@ -104,8 +105,8 @@ struct partitioned_phf  //
             std::vector<std::thread> threads(num_threads);
             auto exe = [&](uint64_t begin, uint64_t end) {
                 for (; begin != end; ++begin) {
-                    m_partitions[begin].offset = offsets[begin];
-                    m_partitions[begin].f.build(builders[begin], config);
+                    partitions[begin].offset = offsets[begin];
+                    partitions[begin].f.build(builders[begin], config);
                 }
             };
 
@@ -123,11 +124,13 @@ struct partitioned_phf  //
             }
         } else {
             for (uint64_t i = 0; i != num_partitions; ++i) {
-                m_partitions[i].offset = offsets[i];
-                m_partitions[i].f.build(builders[i], config);
+                partitions[i].offset = offsets[i];
+                partitions[i].f.build(builders[i], config);
             }
         }
 
+        m_partitions = std::move(partitions);
+
         auto stop = clock_type::now();
 
         return to_microseconds(stop - start);
@@ -147,7 +150,7 @@ struct partitioned_phf  //
 
     uint64_t num_bits_for_pilots() const {
         uint64_t bits = 8 * (sizeof(m_seed) + sizeof(m_num_keys) + sizeof(m_table_size) +
-                             sizeof(uint64_t)  // for std::vector::size
+                             sizeof(uint64_t)  // for span's size
                              ) +
                         m_partitioner.num_bits();
         for (auto const& p : m_partitions) bits += 8 * sizeof(p.offset) + p.f.num_bits_for_pilots();
@@ -200,7 +203,7 @@ struct partitioned_phf  //
     uint64_t m_num_keys;
     uint64_t m_table_size;
     range_bucketer m_partitioner;
-    std::vector<partition> m_partitions;
+    essentials::owning_span<partition> m_partitions;
 };
 
 }  // namespace pthash
\ No newline at end of file
diff --git a/include/utils/dense_encoders.hpp b/include/utils/dense_encoders.hpp
index 422c26f..01e7ece 100644
--- a/include/utils/dense_encoders.hpp
+++ b/include/utils/dense_encoders.hpp
@@ -68,16 +68,17 @@ struct dense_interleaved : dense_encoder {
                 const uint64_t num_partitions,                                         //
                 const uint64_t num_buckets_per_partition, const uint64_t num_threads)  //
     {
-        m_encoders.resize(num_buckets_per_partition);
+        std::vector<Encoder> encoders;
+        encoders.resize(num_buckets_per_partition);
         if (num_threads == 1) {
             for (uint64_t i = 0; i != num_buckets_per_partition; ++i) {
-                m_encoders[i].encode(begin + i * num_partitions, num_partitions);
+                encoders[i].encode(begin + i * num_partitions, num_partitions);
             }
         } else {
             auto exe = [&](uint64_t beginEncoder, uint64_t endEncoder) {
                 for (; beginEncoder != endEncoder; ++beginEncoder) {
-                    m_encoders[beginEncoder].encode(begin + beginEncoder * num_partitions,
-                                                    num_partitions);
+                    encoders[beginEncoder].encode(begin + beginEncoder * num_partitions,
+                                                  num_partitions);
                 }
             };
 
@@ -97,6 +98,7 @@ struct dense_interleaved : dense_encoder {
                 if (t.joinable()) t.join();
             }
         }
+        m_encoders = std::move(encoders);
     }
 
     static std::string name() {
@@ -109,7 +111,7 @@ struct dense_interleaved : dense_encoder {
     }
 
     uint64_t num_bits() const {
-        uint64_t sum = 8 * sizeof(uint64_t);  // for std::vector size
+        uint64_t sum = 8 * sizeof(uint64_t);  // for span' size
         for (auto const& e : m_encoders) sum += e.num_bits();
         return sum;
     }
@@ -130,7 +132,7 @@ struct dense_interleaved : dense_encoder {
         visitor.visit(t.m_encoders);
     }
 
-    std::vector<Encoder> m_encoders;
+    essentials::owning_span<Encoder> m_encoders;
 };
 
 typedef dense_mono<compact> C_mono;
diff --git a/include/utils/encoders.hpp b/include/utils/encoders.hpp
index b55f2ba..a2ff85e 100644
--- a/include/utils/encoders.hpp
+++ b/include/utils/encoders.hpp
@@ -58,8 +58,9 @@ struct partitioned_compact {
         uint64_t num_partitions = (n + partition_size - 1) / partition_size;
         bits::bit_vector::builder bvb;
         bvb.reserve(32 * n);
-        m_bits_per_value.reserve(num_partitions + 1);
-        m_bits_per_value.push_back(0);
+        std::vector<uint32_t> bits_per_value;
+        bits_per_value.reserve(num_partitions + 1);
+        bits_per_value.push_back(0);
         for (uint64_t i = 0, begin_partition = 0; i != num_partitions; ++i) {
             uint64_t end_partition = begin_partition + partition_size;
             if (end_partition > n) end_partition = n;
@@ -76,10 +77,11 @@ struct partitioned_compact {
             for (uint64_t k = begin_partition; k != end_partition; ++k) {
                 bvb.append_bits(*(begin + k), num_bits);
             }
-            assert(m_bits_per_value.back() + num_bits < (1ULL << 32));
-            m_bits_per_value.push_back(m_bits_per_value.back() + num_bits);
+            assert(bits_per_value.back() + num_bits < (1ULL << 32));
+            bits_per_value.push_back(bits_per_value.back() + num_bits);
             begin_partition = end_partition;
         }
+        m_bits_per_value = std::move(bits_per_value);
         bvb.build(m_values);
     }
 
@@ -123,7 +125,7 @@ struct partitioned_compact {
     }
 
     uint64_t m_size;
-    std::vector<uint32_t> m_bits_per_value;
+    essentials::owning_span<uint32_t> m_bits_per_value;
     bits::bit_vector m_values;
 };
 
diff --git a/src/example.cpp b/src/example.cpp
index a33cf84..c9a4c2c 100644
--- a/src/example.cpp
+++ b/src/example.cpp
@@ -8,7 +8,7 @@ int main() {
 
     /* Generate 1M random 64-bit keys as input data. */
     static const uint64_t num_keys = 1'000'000;
-    static const uint64_t seed = 1234567890;
+    static const uint64_t seed = essentials::get_random_seed();
     std::cout << "generating input data..." << std::endl;
     auto keys = distinct_uints<uint64_t>(num_keys, seed);
     // Can also use:
@@ -78,8 +78,23 @@ int main() {
 
     {
         /* Now reload from disk and query. */
+        std::cout << "loading the function from disk..." << std::endl;
         pthash_type other;
         essentials::load(other, output_filename.c_str());
+        if (check(keys.begin(), other)) std::cout << "EVERYTHING OK!" << std::endl;
+        const uint64_t n = std::min<uint64_t>(10, keys.size());
+        for (uint64_t i = 0; i != n; ++i) {
+            std::cout << "f(" << keys[i] << ") = " << other(keys[i]) << '\n';
+            assert(f(keys[i]) == other(keys[i]));
+        }
+    }
+
+    {
+        /* Now mmap from disk and query. */
+        std::cout << "mapping the function from disk..." << std::endl;
+        pthash_type other;
+        essentials::mmap(other, output_filename.c_str());
+        if (check(keys.begin(), other)) std::cout << "EVERYTHING OK!" << std::endl;
         const uint64_t n = std::min<uint64_t>(10, keys.size());
         for (uint64_t i = 0; i != n; ++i) {
             std::cout << "f(" << keys[i] << ") = " << other(keys[i]) << '\n';
@@ -89,4 +104,4 @@ int main() {
 
     std::remove(output_filename.c_str());
     return 0;
-}
\ No newline at end of file
+}