Cleaned up shard files (except VPTree)

Cleaned up shard implementations, fixed a few bugs, and set up some
tests. There's still some work to be done in creating tests for the
weighted sampling operations for the alias and aug btree shards.

7 files changed, 357 insertions, 529 deletions

diff --git a/include/query/wss.h b/include/query/wss.h
index ea36cb2..8797035 100644
--- a/include/query/wss.h
+++ b/include/query/wss.h
@@ -60,7 +60,7 @@ public:
         return res;
     }
 
-    static void* get_buffer_query_state(BufferState<R> *buffer, void *parms) {
+    static void* get_buffer_query_state(BufferView<R> *buffer, void *parms) {
         BufferState<R> *state = new BufferState<R>();
         auto parameters = (Parms<R>*) parms;
         if constexpr (Rejection) {
diff --git a/include/shard/Alias.h b/include/shard/Alias.h
index a234575..f0d1d59 100644
--- a/include/shard/Alias.h
+++ b/include/shard/Alias.h
@@ -14,20 +14,19 @@
 #pragma once
 
 #include <vector>
-#include <cassert>
 
 #include "framework/ShardRequirements.h"
 
-#include "psu-ds/PriorityQueue.h"
-#include "util/Cursor.h"
 #include "psu-ds/Alias.h"
 #include "psu-ds/BloomFilter.h"
 #include "util/bf_config.h"
+#include "util/SortedMerge.h"
 
 using psudb::CACHELINE_SIZE;
 using psudb::BloomFilter;
 using psudb::PriorityQueue;
 using psudb::queue_record;
+using psudb::byte;
 
 namespace de {
 
@@ -41,126 +40,73 @@ private:
     typedef decltype(R::weight) W;
 
 public:
-    Alias(BufferView<R>* buffer)
-    : m_reccnt(0), m_tombstone_cnt(0), m_total_weight(0), m_alias(nullptr), m_bf(nullptr) {
-
-        m_alloc_size = (buffer->get_record_count() * sizeof(Wrapped<R>)) + (CACHELINE_SIZE - (buffer->get_record_count() * sizeof(Wrapped<R>)) % CACHELINE_SIZE);
-        assert(m_alloc_size % CACHELINE_SIZE == 0);
-        m_data = (Wrapped<R>*)std::aligned_alloc(CACHELINE_SIZE, m_alloc_size);
-
-        m_bf = new BloomFilter<R>(BF_FPR, buffer->get_tombstone_count(), BF_HASH_FUNCS);
-
-        size_t offset = 0;
-        m_reccnt = 0;
-        auto base = buffer->get_data();
-        auto stop = base + buffer->get_record_count();
-
-        std::sort(base, stop, std::less<Wrapped<R>>());
-
-        std::vector<W> weights;
-
-        while (base < stop) {
-            if (!(base->is_tombstone()) && (base + 1) < stop) {
-                if (base->rec == (base + 1)->rec && (base + 1)->is_tombstone()) {
-                    base += 2;
-                    wss_cancelations++;
-                    continue;
-                }
-            } else if (base->is_deleted()) {
-                base += 1;
-                continue;
-            }
+    Alias(BufferView<R> buffer)
+        : m_data(nullptr)
+        , m_alias(nullptr)
+        , m_total_weight(0)
+        , m_reccnt(0)
+        , m_tombstone_cnt(0)
+        , m_alloc_size(0)
+        , m_bf(new BloomFilter<R>(BF_FPR, buffer.get_tombstone_count(), BF_HASH_FUNCS)) {
+                       
+
+        m_alloc_size = psudb::sf_aligned_alloc(CACHELINE_SIZE, 
+                                               buffer.get_record_count() * 
+                                                 sizeof(Wrapped<R>), 
+                                               (byte**) &m_data);
+
+        auto res = sorted_array_from_bufferview<R>(std::move(buffer), m_data, m_bf);
+        m_reccnt = res.record_count;
+        m_tombstone_cnt = res.tombstone_count;
 
-            // FIXME: this shouldn't be necessary, but the tagged record
-            // bypass doesn't seem to be working on this code-path, so this
-            // ensures that tagged records from the buffer are able to be
-            // dropped, eventually. It should only need to be &= 1
-            base->header &= 3;
-            m_data[m_reccnt++] = *base;
-            m_total_weight+= base->rec.weight;
-            weights.push_back(base->rec.weight);
-
-            if (m_bf && base->is_tombstone()) {
-                m_tombstone_cnt++;
-                m_bf->insert(base->rec);
+        if (m_reccnt > 0) {
+            std::vector<W> weights;
+            for (size_t i=0; i<m_reccnt; i++) {
+                weights.emplace_back(m_data[i].rec.weight);
+                m_total_weight += m_data[i].rec.weight;
             }
-            
-            base++;
-        }
 
-        if (m_reccnt > 0) {
             build_alias_structure(weights);
         }
     }
 
     Alias(std::vector<Alias*> &shards)
-    : m_reccnt(0), m_tombstone_cnt(0), m_total_weight(0), m_alias(nullptr), m_bf(nullptr) {
-        std::vector<Cursor<Wrapped<R>>> cursors;
-        cursors.reserve(shards.size());
-
-        PriorityQueue<Wrapped<R>> pq(shards.size());
+        : m_data(nullptr)
+        , m_alias(nullptr)
+        , m_total_weight(0)
+        , m_reccnt(0)
+        , m_tombstone_cnt(0)
+        , m_alloc_size(0)
+        , m_bf(nullptr) {
 
         size_t attemp_reccnt = 0;
         size_t tombstone_count = 0;
-        
-        for (size_t i = 0; i < shards.size(); ++i) {
-            if (shards[i]) {
-                auto base = shards[i]->get_data();
-                cursors.emplace_back(Cursor{base, base + shards[i]->get_record_count(), 0, shards[i]->get_record_count()});
-                attemp_reccnt += shards[i]->get_record_count();
-                tombstone_count += shards[i]->get_tombstone_count();
-                pq.push(cursors[i].ptr, i);
-            } else {
-                cursors.emplace_back(Cursor<Wrapped<R>>{nullptr, nullptr, 0, 0});
-            }
-        }
+        auto cursors = build_cursor_vec<R, Alias>(shards, &attemp_reccnt, &tombstone_count);
 
         m_bf = new BloomFilter<R>(BF_FPR, tombstone_count, BF_HASH_FUNCS);
+        m_alloc_size = psudb::sf_aligned_alloc(CACHELINE_SIZE, 
+                                               attemp_reccnt * sizeof(Wrapped<R>),
+                                               (byte **) &m_data);
 
-        m_alloc_size = (attemp_reccnt * sizeof(Wrapped<R>)) + (CACHELINE_SIZE - (attemp_reccnt * sizeof(Wrapped<R>)) % CACHELINE_SIZE);
-        assert(m_alloc_size % CACHELINE_SIZE == 0);
-        m_data = (Wrapped<R>*)std::aligned_alloc(CACHELINE_SIZE, m_alloc_size);
-
-        std::vector<W> weights;
-        
-        while (pq.size()) {
-            auto now = pq.peek();
-            auto next = pq.size() > 1 ? pq.peek(1) : queue_record<Wrapped<R>>{nullptr, 0};
-            if (!now.data->is_tombstone() && next.data != nullptr &&
-                now.data->rec == next.data->rec && next.data->is_tombstone()) {
-                
-                pq.pop(); pq.pop();
-                auto& cursor1 = cursors[now.version];
-                auto& cursor2 = cursors[next.version];
-                if (advance_cursor<Wrapped<R>>(cursor1)) pq.push(cursor1.ptr, now.version);
-                if (advance_cursor<Wrapped<R>>(cursor2)) pq.push(cursor2.ptr, next.version);
-            } else {
-                auto& cursor = cursors[now.version];
-                if (!cursor.ptr->is_deleted()) {
-                    m_data[m_reccnt++] = *cursor.ptr;
-                    m_total_weight += cursor.ptr->rec.weight;
-                    weights.push_back(cursor.ptr->rec.weight);
-                    if (m_bf && cursor.ptr->is_tombstone()) {
-                        ++m_tombstone_cnt;
-                        if (m_bf) m_bf->insert(cursor.ptr->rec);
-                    }
-                }
-                pq.pop();
-                
-                if (advance_cursor<Wrapped<R>>(cursor)) pq.push(cursor.ptr, now.version);
-            }
-        }
+        auto res = sorted_array_merge<R>(cursors, m_data, m_bf);
+        m_reccnt = res.record_count;
+        m_tombstone_cnt = res.tombstone_count;
 
         if (m_reccnt > 0) {
+            std::vector<W> weights;
+            for (size_t i=0; i<m_reccnt; i++) {
+                weights.emplace_back(m_data[i].rec.weight);
+                m_total_weight += m_data[i].rec.weight;
+            }
+
             build_alias_structure(weights);
         }
    }
 
     ~Alias() {
-        if (m_data) free(m_data);
-        if (m_alias) delete m_alias;
-        if (m_bf) delete m_bf;
-
+        free(m_data);
+        delete m_alias;
+        delete m_bf;
     }
 
     Wrapped<R> *point_lookup(const R &rec, bool filter=false) {
@@ -173,7 +119,7 @@ public:
             return nullptr;
         }
 
-        while (idx < m_reccnt && m_data[idx].rec < rec) ++idx;
+        while (idx < (m_reccnt-1) && m_data[idx].rec < rec) ++idx;
 
         if (m_data[idx].rec == rec) {
             return m_data + idx;
@@ -205,7 +151,7 @@ public:
     }
 
     size_t get_aux_memory_usage() {
-        return 0;
+        return (m_bf) ? m_bf->memory_usage() : 0;
     }
 
     W get_total_weight() {
@@ -254,7 +200,6 @@ private:
     W m_total_weight;
     size_t m_reccnt;
     size_t m_tombstone_cnt;
-    size_t m_group_size;
     size_t m_alloc_size;
     BloomFilter<R> *m_bf;
 };
diff --git a/include/shard/AugBTree.h b/include/shard/AugBTree.h
index be664ac..58bd098 100644
--- a/include/shard/AugBTree.h
+++ b/include/shard/AugBTree.h
@@ -16,28 +16,21 @@
 
 #include <vector>
 #include <cassert>
-#include <queue>
-#include <memory>
-#include <concepts>
 
 #include "framework/ShardRequirements.h"
 
-#include "psu-ds/PriorityQueue.h"
-#include "util/Cursor.h"
 #include "psu-ds/Alias.h"
 #include "psu-ds/BloomFilter.h"
 #include "util/bf_config.h"
+#include "util/SortedMerge.h"
 
 using psudb::CACHELINE_SIZE;
 using psudb::BloomFilter;
-using psudb::PriorityQueue;
-using psudb::queue_record;
 using psudb::Alias;
+using psudb::byte;
 
 namespace de {
 
-thread_local size_t wirs_cancelations = 0;
-
 template <WeightedRecordInterface R>
 struct AugBTreeNode {
     struct AugBTreeNode<R> *left, *right;
@@ -54,108 +47,52 @@ private:
     typedef decltype(R::weight) W;
 
 public:
-    AugBTree(MutableBuffer<R>* buffer)
-    : m_reccnt(0), m_tombstone_cnt(0), m_total_weight(0), m_root(nullptr) {
-        m_alloc_size = (buffer->get_record_count() * sizeof(Wrapped<R>)) + (CACHELINE_SIZE - (buffer->get_record_count() * sizeof(Wrapped<R>)) % CACHELINE_SIZE);
-        assert(m_alloc_size % CACHELINE_SIZE == 0);
-        m_data = (Wrapped<R>*)std::aligned_alloc(CACHELINE_SIZE, m_alloc_size);
-
-        m_bf = new BloomFilter<R>(BF_FPR, buffer->get_tombstone_count(), BF_HASH_FUNCS);
-
-        size_t offset = 0;
-        m_reccnt = 0;
-        auto base = buffer->get_data();
-        auto stop = base + buffer->get_record_count();
-
-        std::sort(base, stop, std::less<Wrapped<R>>());
-
-        while (base < stop) {
-            if (!(base->is_tombstone()) && (base + 1) < stop) {
-                if (base->rec == (base + 1)->rec && (base + 1)->is_tombstone()) {
-                    base += 2;
-                    wirs_cancelations++;
-                    continue;
-                }
-            } else if (base->is_deleted()) {
-                base += 1;
-                continue;
-            }
-
-            // FIXME: this shouldn't be necessary, but the tagged record
-            // bypass doesn't seem to be working on this code-path, so this
-            // ensures that tagged records from the buffer are able to be
-            // dropped, eventually. It should only need to be &= 1
-            base->header &= 3;
-            m_data[m_reccnt++] = *base;
-            m_total_weight+= base->rec.weight;
-
-            if (m_bf && base->is_tombstone()) {
-                m_tombstone_cnt++;
-                m_bf->insert(base->rec);
-            }
-            
-            base++;
-        }
+    AugBTree(BufferView<R> buffer)
+    : m_data(nullptr)
+    , m_root(nullptr)
+    , m_reccnt(0)
+    , m_tombstone_cnt(0)
+    , m_group_size(0)
+    , m_alloc_size(0)
+    , m_node_cnt(0)
+    , m_bf(new BloomFilter<R>(BF_FPR, buffer.get_tombstone_count(), BF_HASH_FUNCS))
+    {
+        m_alloc_size = psudb::sf_aligned_alloc(CACHELINE_SIZE, 
+                                               buffer.get_record_count() * 
+                                                 sizeof(Wrapped<R>), 
+                                               (byte**) &m_data);
+
+        auto res = sorted_array_from_bufferview(std::move(buffer), m_data, m_bf);
+        m_reccnt = res.record_count;
+        m_tombstone_cnt = res.tombstone_count;
 
         if (m_reccnt > 0) {
             build_wirs_structure();
         }
     }
 
-    AugBTree(AugBTree** shards, size_t len)
-    : m_reccnt(0), m_tombstone_cnt(0), m_total_weight(0), m_root(nullptr) {
-        std::vector<Cursor<Wrapped<R>>> cursors;
-        cursors.reserve(len);
-
-        PriorityQueue<Wrapped<R>> pq(len);
-
+    AugBTree(std::vector<AugBTree*> shards)
+    : m_data(nullptr)
+    , m_root(nullptr)
+    , m_reccnt(0)
+    , m_tombstone_cnt(0)
+    , m_group_size(0)
+    , m_alloc_size(0)
+    , m_node_cnt(0)
+    , m_bf(nullptr)
+    {
         size_t attemp_reccnt = 0;
         size_t tombstone_count = 0;
-        
-        for (size_t i = 0; i < len; ++i) {
-            if (shards[i]) {
-                auto base = shards[i]->get_data();
-                cursors.emplace_back(Cursor{base, base + shards[i]->get_record_count(), 0, shards[i]->get_record_count()});
-                attemp_reccnt += shards[i]->get_record_count();
-                tombstone_count += shards[i]->get_tombstone_count();
-                pq.push(cursors[i].ptr, i);
-            } else {
-                cursors.emplace_back(Cursor<Wrapped<R>>{nullptr, nullptr, 0, 0});
-            }
-        }
+        auto cursors = build_cursor_vec<R, AugBTree>(shards, &attemp_reccnt, &tombstone_count);
 
         m_bf = new BloomFilter<R>(BF_FPR, tombstone_count, BF_HASH_FUNCS);
+        m_alloc_size = psudb::sf_aligned_alloc(CACHELINE_SIZE, 
+                                               attemp_reccnt * sizeof(Wrapped<R>),
+                                               (byte **) &m_data);
 
-        m_alloc_size = (attemp_reccnt * sizeof(Wrapped<R>)) + (CACHELINE_SIZE - (attemp_reccnt * sizeof(Wrapped<R>)) % CACHELINE_SIZE);
-        assert(m_alloc_size % CACHELINE_SIZE == 0);
-        m_data = (Wrapped<R>*)std::aligned_alloc(CACHELINE_SIZE, m_alloc_size);
-        
-        while (pq.size()) {
-            auto now = pq.peek();
-            auto next = pq.size() > 1 ? pq.peek(1) : queue_record<Wrapped<R>>{nullptr, 0};
-            if (!now.data->is_tombstone() && next.data != nullptr &&
-                now.data->rec == next.data->rec && next.data->is_tombstone()) {
-                
-                pq.pop(); pq.pop();
-                auto& cursor1 = cursors[now.version];
-                auto& cursor2 = cursors[next.version];
-                if (advance_cursor<Wrapped<R>>(cursor1)) pq.push(cursor1.ptr, now.version);
-                if (advance_cursor<Wrapped<R>>(cursor2)) pq.push(cursor2.ptr, next.version);
-            } else {
-                auto& cursor = cursors[now.version];
-                if (!cursor.ptr->is_deleted()) {
-                    m_data[m_reccnt++] = *cursor.ptr;
-                    m_total_weight += cursor.ptr->rec.weight;
-                    if (m_bf && cursor.ptr->is_tombstone()) {
-                        ++m_tombstone_cnt;
-                        if (m_bf) m_bf->insert(cursor.ptr->rec);
-                    }
-                }
-                pq.pop();
-                
-                if (advance_cursor<Wrapped<R>>(cursor)) pq.push(cursor.ptr, now.version);
-            }
-        }
+        auto res = sorted_array_merge<R>(cursors, m_data, m_bf);
+        m_reccnt = res.record_count;
+        m_tombstone_cnt = res.tombstone_count;
 
         if (m_reccnt > 0) {
             build_wirs_structure();
@@ -163,13 +100,12 @@ public:
    }
 
     ~AugBTree() {
-        if (m_data) free(m_data);
+        free(m_data);
         for (size_t i=0; i<m_alias.size(); i++) {
-            if (m_alias[i]) delete m_alias[i];
+            delete m_alias[i];
         }
 
-        if (m_bf) delete m_bf;
-
+        delete m_bf;
         free_tree(m_root);
     }
 
@@ -183,7 +119,7 @@ public:
             return nullptr;
         }
 
-        while (idx < m_reccnt && m_data[idx].rec < rec) ++idx;
+        while (idx < (m_reccnt-1) && m_data[idx].rec < rec) ++idx;
 
         if (m_data[idx].rec == rec) {
             return m_data + idx;
@@ -209,13 +145,12 @@ public:
         return m_data + idx;
     }
 
-
     size_t get_memory_usage() {
         return m_alloc_size + m_node_cnt * sizeof(AugBTreeNode<Wrapped<R>>);
     }
 
     size_t get_aux_memory_usage() {
-        return 0;
+        return (m_bf) ? m_bf->memory_usage() : 0;
     }
 
     size_t get_lower_bound(const K& key) const {
@@ -364,7 +299,6 @@ private:
     Wrapped<R>* m_data;
     std::vector<Alias *> m_alias;
     AugBTreeNode<R>* m_root;
-    W m_total_weight;
     size_t m_reccnt;
     size_t m_tombstone_cnt;
     size_t m_group_size;
diff --git a/include/shard/ISAMTree.h b/include/shard/ISAMTree.h
index 7de9cb1..33ba82f 100644
--- a/include/shard/ISAMTree.h
+++ b/include/shard/ISAMTree.h
@@ -17,9 +17,8 @@
 #include "framework/ShardRequirements.h"
 
 #include "util/bf_config.h"
-#include "psu-ds/PriorityQueue.h"
-#include "util/Cursor.h"
-#include "psu-util/timer.h"
+#include "psu-ds/BloomFilter.h"
+#include "util/SortedMerge.h"
 
 using psudb::CACHELINE_SIZE;
 using psudb::BloomFilter;
@@ -61,60 +60,18 @@ public:
         , m_alloc_size(0)
         , m_data(nullptr)
     {
-        TIMER_INIT();
-
         m_alloc_size = psudb::sf_aligned_alloc(CACHELINE_SIZE, 
                                                buffer.get_record_count() * 
                                                  sizeof(Wrapped<R>), 
                                                (byte**) &m_data);
 
-        TIMER_START();
-        auto temp_buffer = (Wrapped<R> *) psudb::sf_aligned_calloc(CACHELINE_SIZE, buffer.get_record_count(), sizeof(Wrapped<R>));
-        buffer.copy_to_buffer((byte *) temp_buffer);
-
-        auto base = temp_buffer;
-        auto stop = base + buffer.get_record_count();
-        std::sort(base, stop, std::less<Wrapped<R>>());
-        TIMER_STOP();
-
-        auto sort_time = TIMER_RESULT();
-
-        TIMER_START();
-        while (base < stop) {
-            if (!base->is_tombstone() && (base + 1 < stop)
-                && base->rec == (base + 1)->rec  && (base + 1)->is_tombstone()) {
-                base += 2;
-                continue;
-            } else if (base->is_deleted()) {
-                base += 1;
-                continue;
-            }
-
-            // FIXME: this shouldn't be necessary, but the tagged record
-            // bypass doesn't seem to be working on this code-path, so this
-            // ensures that tagged records from the buffer are able to be
-            // dropped, eventually. It should only need to be &= 1
-            base->header &= 3;
-            m_data[m_reccnt++] = *base;
-            if (m_bf && base->is_tombstone()) {
-                ++m_tombstone_cnt;
-                m_bf->insert(base->rec);
-            }
-
-            base++;
-        }
-
-        TIMER_STOP();
-        auto copy_time = TIMER_RESULT();
+        auto res = sorted_array_from_bufferview(std::move(buffer), m_data, m_bf);
+        m_reccnt = res.record_count;
+        m_tombstone_cnt = res.tombstone_count;
 
-        TIMER_START();
         if (m_reccnt > 0) {
             build_internal_levels();
         }
-        TIMER_STOP();
-        auto level_time = TIMER_RESULT();
-
-        free(temp_buffer);
     }
 
     ISAMTree(std::vector<ISAMTree*> &shards)
@@ -128,58 +85,18 @@ public:
         , m_alloc_size(0)
         , m_data(nullptr)
     {
-        std::vector<Cursor<Wrapped<R>>> cursors;
-        cursors.reserve(shards.size());
-
-        PriorityQueue<Wrapped<R>> pq(shards.size());
-
         size_t attemp_reccnt = 0;
         size_t tombstone_count = 0;
-        
-        for (size_t i = 0; i < shards.size(); ++i) {
-            if (shards[i]) {
-                auto base = shards[i]->get_data();
-                cursors.emplace_back(Cursor{base, base + shards[i]->get_record_count(), 0, shards[i]->get_record_count()});
-                attemp_reccnt += shards[i]->get_record_count();
-                tombstone_count += shards[i]->get_tombstone_count();
-                pq.push(cursors[i].ptr, i);
-            } else {
-                cursors.emplace_back(Cursor<Wrapped<R>>{nullptr, nullptr, 0, 0});
-            }
-        }
+        auto cursors = build_cursor_vec<R, ISAMTree>(shards, &attemp_reccnt, &tombstone_count);
 
         m_bf = new BloomFilter<R>(BF_FPR, tombstone_count, BF_HASH_FUNCS);
         m_alloc_size = psudb::sf_aligned_alloc(CACHELINE_SIZE, 
                                                attemp_reccnt * sizeof(Wrapped<R>),
                                                (byte **) &m_data);
 
-        while (pq.size()) {
-            auto now = pq.peek();
-            auto next = pq.size() > 1 ? pq.peek(1) : queue_record<Wrapped<R>>{nullptr, 0};
-            if (!now.data->is_tombstone() && next.data != nullptr &&
-                now.data->rec == next.data->rec && next.data->is_tombstone()) {
-                
-                pq.pop(); pq.pop();
-                auto& cursor1 = cursors[now.version];
-                auto& cursor2 = cursors[next.version];
-                if (advance_cursor(cursor1)) pq.push(cursor1.ptr, now.version);
-                if (advance_cursor(cursor2)) pq.push(cursor2.ptr, next.version);
-            } else {
-                auto& cursor = cursors[now.version];
-                if (!cursor.ptr->is_deleted()) {
-                    m_data[m_reccnt++] = *cursor.ptr;
-                    if (cursor.ptr->is_tombstone()) {
-                        //fprintf(stderr, "ISAM: Tombstone from shard %ld next record from shard %ld\n",
-                                //now.version, next.version);
-                        ++m_tombstone_cnt;
-                        m_bf->insert(cursor.ptr->rec);
-                    }
-                }
-                pq.pop();
-                
-                if (advance_cursor(cursor)) pq.push(cursor.ptr, now.version);
-            }
-        }
+        auto res = sorted_array_merge<R>(cursors, m_data, m_bf);
+        m_reccnt = res.record_count;
+        m_tombstone_cnt = res.tombstone_count;
 
         if (m_reccnt > 0) {
             build_internal_levels();
@@ -225,11 +142,11 @@ public:
 
 
     size_t get_memory_usage() {
-        return m_alloc_size;
+        return m_alloc_size + m_internal_node_cnt * NODE_SZ;
     }
 
     size_t get_aux_memory_usage() {
-        return m_bf->memory_usage();
+        return (m_bf) ? m_bf->memory_usage() : 0;
     }
 
     /* SortedShardInterface methods */
diff --git a/include/shard/PGM.h b/include/shard/PGM.h
index 13db26a..8031870 100644
--- a/include/shard/PGM.h
+++ b/include/shard/PGM.h
@@ -14,24 +14,19 @@
 
 
 #include <vector>
-#include <cassert>
-#include <queue>
-#include <memory>
-#include <concepts>
 
 #include "framework/ShardRequirements.h"
 
 #include "pgm/pgm_index.hpp"
-#include "psu-ds/PriorityQueue.h"
-#include "util/Cursor.h"
 #include "psu-ds/BloomFilter.h"
+#include "util/SortedMerge.h"
 #include "util/bf_config.h"
 
 using psudb::CACHELINE_SIZE;
 using psudb::BloomFilter;
 using psudb::PriorityQueue;
 using psudb::queue_record;
-using psudb::Alias;
+using psudb::byte;
 
 namespace de {
 
@@ -41,111 +36,65 @@ private:
     typedef decltype(R::key) K;
     typedef decltype(R::value) V;
 
-
 public:
-    PGM(MutableBuffer<R>* buffer)
-    : m_reccnt(0), m_tombstone_cnt(0) {
-
-        m_alloc_size = (buffer->get_record_count() * sizeof(Wrapped<R>)) + (CACHELINE_SIZE - (buffer->get_record_count() * sizeof(Wrapped<R>)) % CACHELINE_SIZE);
-        assert(m_alloc_size % CACHELINE_SIZE == 0);
-        m_data = (Wrapped<R>*)std::aligned_alloc(CACHELINE_SIZE, m_alloc_size);
-        std::vector<K> keys;
-
-        size_t offset = 0;
-        m_reccnt = 0;
-        auto base = buffer->get_data();
-        auto stop = base + buffer->get_record_count();
+    PGM(BufferView<R> buffer)
+        : m_data(nullptr)
+        , m_bf(new BloomFilter<R>(BF_FPR, buffer.get_tombstone_count(), BF_HASH_FUNCS))
+        , m_reccnt(0)
+        , m_tombstone_cnt(0)
+        , m_alloc_size(0) {
+
+        m_alloc_size = psudb::sf_aligned_alloc(CACHELINE_SIZE, 
+                                               buffer.get_record_count() * 
+                                                 sizeof(Wrapped<R>), 
+                                               (byte**) &m_data);
+        auto res = sorted_array_from_bufferview<R>(std::move(buffer), m_data, m_bf);
+        m_reccnt = res.record_count;
+        m_tombstone_cnt = res.tombstone_count;
 
-        std::sort(base, stop, std::less<Wrapped<R>>());
-
-        K min_key = base->rec.key;
-        K max_key = (stop - 1)->rec.key;
-
-        while (base < stop) {
-            if (!(base->is_tombstone()) && (base + 1) < stop) {
-                if (base->rec == (base + 1)->rec && (base + 1)->is_tombstone()) {
-                    base += 2;
-                    continue;
-                }
-            } else if (base->is_deleted()) {
-                base += 1;
-                continue;
+        if (m_reccnt > 0) {
+            std::vector<K> keys;
+            for (size_t i=0; i<m_reccnt; i++) {
+                keys.emplace_back(m_data[i].rec.key);
             }
 
-            // FIXME: this shouldn't be necessary, but the tagged record
-            // bypass doesn't seem to be working on this code-path, so this
-            // ensures that tagged records from the buffer are able to be
-            // dropped, eventually. It should only need to be &= 1
-            base->header &= 3;
-            m_data[m_reccnt++] = *base;
-            keys.emplace_back(base->rec.key);
-            base++;
-        }
-
-        if (m_reccnt > 0) {
             m_pgm = pgm::PGMIndex<K, epsilon>(keys);
         }
     }
 
-    PGM(PGM** shards, size_t len)
-    : m_reccnt(0), m_tombstone_cnt(0) {
-        std::vector<Cursor<Wrapped<R>>> cursors;
-        cursors.reserve(len);
-
-        PriorityQueue<Wrapped<R>> pq(len);
-
+    PGM(std::vector<PGM*> shards)
+        : m_data(nullptr)
+        , m_bf(nullptr)
+        , m_reccnt(0)
+        , m_tombstone_cnt(0)
+        , m_alloc_size(0) {
+        
         size_t attemp_reccnt = 0;
         size_t tombstone_count = 0;
-        
-        for (size_t i = 0; i < len; ++i) {
-            if (shards[i]) {
-                auto base = shards[i]->get_data();
-                cursors.emplace_back(Cursor{base, base + shards[i]->get_record_count(), 0, shards[i]->get_record_count()});
-                attemp_reccnt += shards[i]->get_record_count();
-                tombstone_count += shards[i]->get_tombstone_count();
-                pq.push(cursors[i].ptr, i);
-
-            } else {
-                cursors.emplace_back(Cursor<Wrapped<R>>{nullptr, nullptr, 0, 0});
-            }
-        }
+        auto cursors = build_cursor_vec<R, PGM>(shards, &attemp_reccnt, &tombstone_count);
 
-        m_alloc_size = (attemp_reccnt * sizeof(Wrapped<R>)) + (CACHELINE_SIZE - (attemp_reccnt * sizeof(Wrapped<R>)) % CACHELINE_SIZE);
-        assert(m_alloc_size % CACHELINE_SIZE == 0);
-        m_data = (Wrapped<R>*)std::aligned_alloc(CACHELINE_SIZE, m_alloc_size);
-
-        std::vector<K> keys;
-
-        while (pq.size()) {
-            auto now = pq.peek();
-            auto next = pq.size() > 1 ? pq.peek(1) : queue_record<Wrapped<R>>{nullptr, 0};
-            if (!now.data->is_tombstone() && next.data != nullptr &&
-                now.data->rec == next.data->rec && next.data->is_tombstone()) {
-                
-                pq.pop(); pq.pop();
-                auto& cursor1 = cursors[now.version];
-                auto& cursor2 = cursors[next.version];
-                if (advance_cursor<Wrapped<R>>(cursor1)) pq.push(cursor1.ptr, now.version);
-                if (advance_cursor<Wrapped<R>>(cursor2)) pq.push(cursor2.ptr, next.version);
-            } else {
-                auto& cursor = cursors[now.version];
-                if (!cursor.ptr->is_deleted()) {
-                    m_data[m_reccnt++] = *cursor.ptr;
-                    keys.emplace_back(cursor.ptr->rec.key);
-                }
-                pq.pop();
-                
-                if (advance_cursor<Wrapped<R>>(cursor)) pq.push(cursor.ptr, now.version);
-            }
-        }
+        m_bf = new BloomFilter<R>(BF_FPR, tombstone_count, BF_HASH_FUNCS);
+        m_alloc_size = psudb::sf_aligned_alloc(CACHELINE_SIZE, 
+                                               attemp_reccnt * sizeof(Wrapped<R>),
+                                               (byte **) &m_data);
+
+        auto res = sorted_array_merge<R>(cursors, m_data, m_bf);
+        m_reccnt = res.record_count;
+        m_tombstone_cnt = res.tombstone_count;
 
         if (m_reccnt > 0) {
+            std::vector<K> keys;
+            for (size_t i=0; i<m_reccnt; i++) {
+                keys.emplace_back(m_data[i].rec.key);
+            }
+
             m_pgm = pgm::PGMIndex<K, epsilon>(keys);
         }
    }
 
     ~PGM() {
-        if (m_data) free(m_data);
+        free(m_data);
+        delete m_bf;
     }
 
     Wrapped<R> *point_lookup(const R &rec, bool filter=false) {
@@ -186,7 +135,7 @@ public:
     }
 
     size_t get_aux_memory_usage() {
-        return 0;
+        return (m_bf) ? m_bf->memory_usage() : 0;
     }
 
     size_t get_lower_bound(const K& key) const {
@@ -228,6 +177,7 @@ public:
 
 private:
     Wrapped<R>* m_data;
+    BloomFilter<R> *m_bf;
     size_t m_reccnt;
     size_t m_tombstone_cnt;
     size_t m_alloc_size;
diff --git a/include/shard/TrieSpline.h b/include/shard/TrieSpline.h
index 9473177..f9fb3cb 100644
--- a/include/shard/TrieSpline.h
+++ b/include/shard/TrieSpline.h
@@ -15,11 +15,9 @@
 
 #include "framework/ShardRequirements.h"
 #include "ts/builder.h"
-#include "psu-ds/PriorityQueue.h"
-#include "util/Cursor.h"
 #include "psu-ds/BloomFilter.h"
 #include "util/bf_config.h"
-#include "psu-util/timer.h"
+#include "util/SortedMerge.h"
 
 using psudb::CACHELINE_SIZE;
 using psudb::BloomFilter;
@@ -45,78 +43,26 @@ public:
         , m_min_key(0)
         , m_bf(new BloomFilter<R>(BF_FPR, buffer.get_tombstone_count(), BF_HASH_FUNCS))
     {
-        TIMER_INIT();
-
         m_alloc_size = psudb::sf_aligned_alloc(CACHELINE_SIZE, 
                                                buffer.get_record_count() * 
                                                  sizeof(Wrapped<R>), 
                                                (byte**) &m_data);
 
-        TIMER_START();
-        auto temp_buffer = (Wrapped<R> *) psudb::sf_aligned_calloc(CACHELINE_SIZE, buffer.get_record_count(), sizeof(Wrapped<R>));
-        buffer.copy_to_buffer((byte *) temp_buffer);
-
-        auto base = temp_buffer;
-        auto stop = base + buffer.get_record_count();
-        std::sort(base, stop, std::less<Wrapped<R>>());
-
-        K min_key = base->rec.key;
-        K max_key = (stop-1)->rec.key;
-        TIMER_STOP();
-
-        auto sort_time = TIMER_RESULT();
-
-        TIMER_START();
-        auto bldr = ts::Builder<K>(min_key, max_key, E);
-        while (base < stop) {
-            if (!base->is_tombstone() && (base + 1 < stop)
-                && base->rec == (base + 1)->rec  && (base + 1)->is_tombstone()) {
-                base += 2;
-                continue;
-            } else if (base->is_deleted()) {
-                base += 1;
-                continue;
-            }
+        auto res = sorted_array_from_bufferview(std::move(buffer), m_data, m_bf);
+        m_reccnt = res.record_count;
+        m_tombstone_cnt = res.tombstone_count;
 
-            // FIXME: this shouldn't be necessary, but the tagged record
-            // bypass doesn't seem to be working on this code-path, so this
-            // ensures that tagged records from the buffer are able to be
-            // dropped, eventually. It should only need to be &= 1
-            base->header &= 3;
-            m_data[m_reccnt++] = *base;
-            bldr.AddKey(base->rec.key);
-            if (m_bf && base->is_tombstone()) {
-                ++m_tombstone_cnt;
-                m_bf->insert(base->rec);
-            }
+        if (m_reccnt > 0) {
+            m_min_key = m_data[0].rec.key;
+            m_max_key = m_data[m_reccnt-1].rec.key;
 
-            /*
-             * determine the "true" min/max keys based on the scan. This is
-             * to avoid situations where the min/max in the input array
-             * are deleted and don't survive into the structure itself.
-             */
-            if (m_reccnt == 0) {
-                m_max_key = m_min_key = base->rec.key;
-            } else if (base->rec.key > m_max_key) {
-                m_max_key = base->rec.key;
-            } else if (base->rec.key < m_min_key) {
-                m_min_key = base->rec.key;
+            auto bldr = ts::Builder<K>(m_min_key, m_max_key, E);
+            for (size_t i=0; i<m_reccnt; i++) {
+                bldr.AddKey(m_data[i].rec.key);
             }
 
-            base++;
-        }
-
-        TIMER_STOP();
-        auto copy_time = TIMER_RESULT();
-
-        TIMER_START();
-        if (m_reccnt > 0) {
             m_ts = bldr.Finalize();
         }
-        TIMER_STOP();
-        auto level_time = TIMER_RESULT();
-
-        free(temp_buffer);
     }
 
     TrieSpline(std::vector<TrieSpline*> &shards) 
@@ -128,77 +74,28 @@ public:
         , m_min_key(0)
         , m_bf(nullptr)
     {
-
-        std::vector<Cursor<Wrapped<R>>> cursors;
-        cursors.reserve(shards.size());
-
-        PriorityQueue<Wrapped<R>> pq(shards.size());
-
         size_t attemp_reccnt = 0;
         size_t tombstone_count = 0;
-
-        /*
-         * Initialize m_max_key and m_min_key using the values from the
-         * first shard. These will later be updated when building
-         * the initial priority queue to their true values.
-         */
-        m_max_key = shards[0]->m_max_key;
-        m_min_key = shards[0]->m_min_key;
+        auto cursors = build_cursor_vec<R, TrieSpline>(shards, &attemp_reccnt, &tombstone_count);
         
-        for (size_t i = 0; i < shards.size(); ++i) {
-            if (shards[i]) {
-                auto base = shards[i]->get_data();
-                cursors.emplace_back(Cursor{base, base + shards[i]->get_record_count(), 0, shards[i]->get_record_count()});
-                attemp_reccnt += shards[i]->get_record_count();
-                tombstone_count += shards[i]->get_tombstone_count();
-                pq.push(cursors[i].ptr, i);
-
-                if (shards[i]->m_max_key > m_max_key) {
-                    m_max_key = shards[i]->m_max_key;
-                } 
-
-                if (shards[i]->m_min_key < m_min_key) {
-                    m_min_key = shards[i]->m_min_key;
-                }
-            } else {
-                cursors.emplace_back(Cursor<Wrapped<R>>{nullptr, nullptr, 0, 0});
-            }
-        }
-
         m_bf = new BloomFilter<R>(BF_FPR, tombstone_count, BF_HASH_FUNCS);
         m_alloc_size = psudb::sf_aligned_alloc(CACHELINE_SIZE, 
                                                attemp_reccnt * sizeof(Wrapped<R>),
                                                (byte **) &m_data);
 
-        auto bldr = ts::Builder<K>(m_min_key, m_max_key, E);
-        while (pq.size()) {
-            auto now = pq.peek();
-            auto next = pq.size() > 1 ? pq.peek(1) : queue_record<Wrapped<R>>{nullptr, 0};
-            if (!now.data->is_tombstone() && next.data != nullptr &&
-                now.data->rec == next.data->rec && next.data->is_tombstone()) {
-                
-                pq.pop(); pq.pop();
-                auto& cursor1 = cursors[now.version];
-                auto& cursor2 = cursors[next.version];
-                if (advance_cursor(cursor1)) pq.push(cursor1.ptr, now.version);
-                if (advance_cursor(cursor2)) pq.push(cursor2.ptr, next.version);
-            } else {
-                auto& cursor = cursors[now.version];
-                if (!cursor.ptr->is_deleted()) {
-                    m_data[m_reccnt++] = *cursor.ptr;
-                    bldr.AddKey(cursor.ptr->rec.key);
-                    if (cursor.ptr->is_tombstone()) {
-                        ++m_tombstone_cnt;
-                        m_bf->insert(cursor.ptr->rec);
-                    }
-                }
-                pq.pop();
-                
-                if (advance_cursor(cursor)) pq.push(cursor.ptr, now.version);
-            }
-        }
+        auto res = sorted_array_merge<R>(cursors, m_data, m_bf);
+        m_reccnt = res.record_count;
+        m_tombstone_cnt = res.tombstone_count;
 
         if (m_reccnt > 0) {
+            m_min_key = m_data[0].rec.key;
+            m_max_key = m_data[m_reccnt-1].rec.key;
+
+            auto bldr = ts::Builder<K>(m_min_key, m_max_key, E);
+            for (size_t i=0; i<m_reccnt; i++) {
+                bldr.AddKey(m_data[i].rec.key);
+            }
+
             m_ts = bldr.Finalize();
         }
     }
@@ -250,7 +147,7 @@ public:
     }
 
     size_t get_aux_memory_usage() {
-        return 0;
+        return (m_bf) ? m_bf->memory_usage() : 0;
     }
 
     size_t get_lower_bound(const K& key) const {
diff --git a/include/util/SortedMerge.h b/include/util/SortedMerge.h
new file mode 100644
index 0000000..ed47acb
--- /dev/null
+++ b/include/util/SortedMerge.h
@@ -0,0 +1,185 @@
+/*
+ * include/util/SortedMerge.h
+ *
+ * Copyright (C) 2023 Douglas B. Rumbaugh <drumbaugh@psu.edu> 
+ *                    Dong Xie <dongx@psu.edu>
+ *
+ * Distributed under the Modified BSD License.
+ *
+ * A sorted array merge routine for use in Shard construction, as many
+ * shards will use a sorted array to represent their data. Also encapsulates 
+ * the necessary tombstone-cancellation logic.
+ *
+ * FIXME: include generic per-record processing functionality for Shards that 
+ * need it, to avoid needing to reprocess the array in the shard after
+ * creation.
+ */
+#pragma once
+
+#include "util/Cursor.h"
+#include "framework/interface/Shard.h"
+#include "psu-ds/PriorityQueue.h"
+
+namespace de {
+
+using psudb::PriorityQueue;
+using psudb::BloomFilter;
+using psudb::queue_record;
+using psudb::byte;
+using psudb::CACHELINE_SIZE;
+
+struct merge_info {
+    size_t record_count;
+    size_t tombstone_count;
+};
+
+
+template <RecordInterface R, ShardInterface<R> S>
+static std::vector<Cursor<Wrapped<R>>> build_cursor_vec(std::vector<S*> &shards, size_t *reccnt, size_t *tscnt) {
+    std::vector<Cursor<Wrapped<R>>> cursors;
+    cursors.reserve(shards.size());
+
+    *reccnt = 0;
+    *tscnt = 0;
+    
+    for (size_t i = 0; i < shards.size(); ++i) {
+        if (shards[i]) {
+            auto base = shards[i]->get_data();
+            cursors.emplace_back(Cursor{base, base + shards[i]->get_record_count(), 0, shards[i]->get_record_count()});
+            *reccnt += shards[i]->get_record_count();
+            *tscnt += shards[i]->get_tombstone_count();
+        } else {
+            cursors.emplace_back(Cursor<Wrapped<R>>{nullptr, nullptr, 0, 0});
+        }
+    }
+
+    return cursors;
+}
+
+/*
+ * 
+ */
+template <RecordInterface R>
+static merge_info sorted_array_from_bufferview(BufferView<R> bv, 
+                                               Wrapped<R> *buffer,
+                                               psudb::BloomFilter<R> *bf=nullptr) {
+    /*
+     * Copy the contents of the buffer view into a temporary buffer, and
+     * sort them. We still need to iterate over these temporary records to 
+     * apply tombstone/deleted record filtering, as well as any possible
+     * per-record processing that is required by the shard being built.
+     */
+    auto temp_buffer = (Wrapped<R> *) psudb::sf_aligned_calloc(CACHELINE_SIZE, 
+                                                               bv.get_record_count(), 
+                                                               sizeof(Wrapped<R>));
+    bv.copy_to_buffer((byte *) temp_buffer);
+
+    auto base = temp_buffer;
+    auto stop = base + bv.get_record_count();
+    std::sort(base, stop, std::less<Wrapped<R>>());
+
+    merge_info info = {0, 0};
+
+    /* 
+     * Iterate over the temporary buffer to process the records, copying
+     * them into buffer as needed
+     */
+    while (base < stop) {
+        if (!base->is_tombstone() && (base + 1 < stop)
+            && base->rec == (base + 1)->rec  && (base + 1)->is_tombstone()) {
+            base += 2;
+            continue;
+        } else if (base->is_deleted()) {
+            base += 1;
+            continue;
+        }
+
+        // fixme: this shouldn't be necessary, but the tagged record
+        // bypass doesn't seem to be working on this code-path, so this
+        // ensures that tagged records from the buffer are able to be
+        // dropped, eventually. it should only need to be &= 1
+        base->header &= 3;
+        buffer[info.record_count++] = *base;
+
+        if (base->is_tombstone()) {
+            info.tombstone_count++;
+            if (bf){
+                bf->insert(base->rec);
+            }
+        }
+
+        base++;
+    }
+
+    free(temp_buffer);
+    return info;
+}
+
+/*
+ * Perform a sorted merge of the records within cursors into the provided
+ * buffer. Includes tombstone and tagged delete cancellation logic, and
+ * will insert tombstones into a bloom filter, if one is provided. 
+ *
+ * The behavior of this function is undefined if the provided buffer does
+ * not have space to contain all of the records within the input cursors.
+ */
+template <RecordInterface R>
+static merge_info sorted_array_merge(std::vector<Cursor<Wrapped<R>>> &cursors, 
+                              Wrapped<R> *buffer, 
+                              psudb::BloomFilter<R> *bf=nullptr) {
+    
+    // FIXME: For smaller cursor arrays, it may be more efficient to skip
+    //        the priority queue and just do a scan.
+    PriorityQueue<Wrapped<R>> pq(cursors.size());
+    for (size_t i=0; i<cursors.size(); i++) {
+        pq.push(cursors[i].ptr, i);
+    }
+
+    merge_info info = {0, 0};
+    while (pq.size()) {
+        auto now = pq.peek();
+        auto next = pq.size() > 1 ? pq.peek(1) : queue_record<Wrapped<R>>{nullptr, 0};
+        /* 
+         * if the current record is not a tombstone, and the next record is
+         * a tombstone that matches the current one, then the current one
+         * has been deleted, and both it and its tombstone can be skipped
+         * over.
+         */
+        if (!now.data->is_tombstone() && next.data != nullptr &&
+            now.data->rec == next.data->rec && next.data->is_tombstone()) {
+            
+            pq.pop(); pq.pop();
+            auto& cursor1 = cursors[now.version];
+            auto& cursor2 = cursors[next.version];
+            if (advance_cursor(cursor1)) pq.push(cursor1.ptr, now.version);
+            if (advance_cursor(cursor2)) pq.push(cursor2.ptr, next.version);
+        } else {
+            auto& cursor = cursors[now.version];
+            /* skip over records that have been deleted via tagging */
+            if (!cursor.ptr->is_deleted()) {
+                buffer[info.record_count++] = *cursor.ptr;
+
+                /*  
+                 * if the record is a tombstone, increment the ts count and 
+                 * insert it into the bloom filter if one has been
+                 * provided.
+                 */
+                if (cursor.ptr->is_tombstone()) {
+                    info.tombstone_count++;
+                    if (bf) {
+                        bf->insert(cursor.ptr->rec);
+                    }
+                }
+            }
+            pq.pop();
+            
+            if (advance_cursor(cursor)) pq.push(cursor.ptr, now.version);
+        }
+    }
+
+    return info;
+}
+
+
+
+}