KIKIMR-19521 BTreeIndex Charge Interface

17 files changed, 325 insertions, 167 deletions

diff --git a/ydb/core/tablet_flat/CMakeLists.darwin-arm64.txt b/ydb/core/tablet_flat/CMakeLists.darwin-arm64.txt
index dcc93ab95c..c6d0640e5f 100644
--- a/ydb/core/tablet_flat/CMakeLists.darwin-arm64.txt
+++ b/ydb/core/tablet_flat/CMakeLists.darwin-arm64.txt
@@ -107,6 +107,8 @@ target_sources(ydb-core-tablet_flat PRIVATE
   ${CMAKE_SOURCE_DIR}/ydb/core/tablet_flat/flat_mem_warm.cpp
   ${CMAKE_SOURCE_DIR}/ydb/core/tablet_flat/flat_sausagecache.cpp
   ${CMAKE_SOURCE_DIR}/ydb/core/tablet_flat/flat_sausage_meta.cpp
+  ${CMAKE_SOURCE_DIR}/ydb/core/tablet_flat/flat_part_charge_create.cpp
+  ${CMAKE_SOURCE_DIR}/ydb/core/tablet_flat/flat_part_charge_range.cpp
   ${CMAKE_SOURCE_DIR}/ydb/core/tablet_flat/flat_page_label.cpp
   ${CMAKE_SOURCE_DIR}/ydb/core/tablet_flat/flat_part_dump.cpp
   ${CMAKE_SOURCE_DIR}/ydb/core/tablet_flat/flat_part_iter_multi.cpp
diff --git a/ydb/core/tablet_flat/CMakeLists.darwin-x86_64.txt b/ydb/core/tablet_flat/CMakeLists.darwin-x86_64.txt
index dcc93ab95c..c6d0640e5f 100644
--- a/ydb/core/tablet_flat/CMakeLists.darwin-x86_64.txt
+++ b/ydb/core/tablet_flat/CMakeLists.darwin-x86_64.txt
@@ -107,6 +107,8 @@ target_sources(ydb-core-tablet_flat PRIVATE
   ${CMAKE_SOURCE_DIR}/ydb/core/tablet_flat/flat_mem_warm.cpp
   ${CMAKE_SOURCE_DIR}/ydb/core/tablet_flat/flat_sausagecache.cpp
   ${CMAKE_SOURCE_DIR}/ydb/core/tablet_flat/flat_sausage_meta.cpp
+  ${CMAKE_SOURCE_DIR}/ydb/core/tablet_flat/flat_part_charge_create.cpp
+  ${CMAKE_SOURCE_DIR}/ydb/core/tablet_flat/flat_part_charge_range.cpp
   ${CMAKE_SOURCE_DIR}/ydb/core/tablet_flat/flat_page_label.cpp
   ${CMAKE_SOURCE_DIR}/ydb/core/tablet_flat/flat_part_dump.cpp
   ${CMAKE_SOURCE_DIR}/ydb/core/tablet_flat/flat_part_iter_multi.cpp
diff --git a/ydb/core/tablet_flat/CMakeLists.linux-aarch64.txt b/ydb/core/tablet_flat/CMakeLists.linux-aarch64.txt
index 0f0cc8999b..8dd469d197 100644
--- a/ydb/core/tablet_flat/CMakeLists.linux-aarch64.txt
+++ b/ydb/core/tablet_flat/CMakeLists.linux-aarch64.txt
@@ -108,6 +108,8 @@ target_sources(ydb-core-tablet_flat PRIVATE
   ${CMAKE_SOURCE_DIR}/ydb/core/tablet_flat/flat_mem_warm.cpp
   ${CMAKE_SOURCE_DIR}/ydb/core/tablet_flat/flat_sausagecache.cpp
   ${CMAKE_SOURCE_DIR}/ydb/core/tablet_flat/flat_sausage_meta.cpp
+  ${CMAKE_SOURCE_DIR}/ydb/core/tablet_flat/flat_part_charge_create.cpp
+  ${CMAKE_SOURCE_DIR}/ydb/core/tablet_flat/flat_part_charge_range.cpp
   ${CMAKE_SOURCE_DIR}/ydb/core/tablet_flat/flat_page_label.cpp
   ${CMAKE_SOURCE_DIR}/ydb/core/tablet_flat/flat_part_dump.cpp
   ${CMAKE_SOURCE_DIR}/ydb/core/tablet_flat/flat_part_iter_multi.cpp
diff --git a/ydb/core/tablet_flat/CMakeLists.linux-x86_64.txt b/ydb/core/tablet_flat/CMakeLists.linux-x86_64.txt
index 0f0cc8999b..8dd469d197 100644
--- a/ydb/core/tablet_flat/CMakeLists.linux-x86_64.txt
+++ b/ydb/core/tablet_flat/CMakeLists.linux-x86_64.txt
@@ -108,6 +108,8 @@ target_sources(ydb-core-tablet_flat PRIVATE
   ${CMAKE_SOURCE_DIR}/ydb/core/tablet_flat/flat_mem_warm.cpp
   ${CMAKE_SOURCE_DIR}/ydb/core/tablet_flat/flat_sausagecache.cpp
   ${CMAKE_SOURCE_DIR}/ydb/core/tablet_flat/flat_sausage_meta.cpp
+  ${CMAKE_SOURCE_DIR}/ydb/core/tablet_flat/flat_part_charge_create.cpp
+  ${CMAKE_SOURCE_DIR}/ydb/core/tablet_flat/flat_part_charge_range.cpp
   ${CMAKE_SOURCE_DIR}/ydb/core/tablet_flat/flat_page_label.cpp
   ${CMAKE_SOURCE_DIR}/ydb/core/tablet_flat/flat_part_dump.cpp
   ${CMAKE_SOURCE_DIR}/ydb/core/tablet_flat/flat_part_iter_multi.cpp
diff --git a/ydb/core/tablet_flat/CMakeLists.windows-x86_64.txt b/ydb/core/tablet_flat/CMakeLists.windows-x86_64.txt
index dcc93ab95c..c6d0640e5f 100644
--- a/ydb/core/tablet_flat/CMakeLists.windows-x86_64.txt
+++ b/ydb/core/tablet_flat/CMakeLists.windows-x86_64.txt
@@ -107,6 +107,8 @@ target_sources(ydb-core-tablet_flat PRIVATE
   ${CMAKE_SOURCE_DIR}/ydb/core/tablet_flat/flat_mem_warm.cpp
   ${CMAKE_SOURCE_DIR}/ydb/core/tablet_flat/flat_sausagecache.cpp
   ${CMAKE_SOURCE_DIR}/ydb/core/tablet_flat/flat_sausage_meta.cpp
+  ${CMAKE_SOURCE_DIR}/ydb/core/tablet_flat/flat_part_charge_create.cpp
+  ${CMAKE_SOURCE_DIR}/ydb/core/tablet_flat/flat_part_charge_range.cpp
   ${CMAKE_SOURCE_DIR}/ydb/core/tablet_flat/flat_page_label.cpp
   ${CMAKE_SOURCE_DIR}/ydb/core/tablet_flat/flat_part_dump.cpp
   ${CMAKE_SOURCE_DIR}/ydb/core/tablet_flat/flat_part_iter_multi.cpp
diff --git a/ydb/core/tablet_flat/benchmark/b_charge.cpp b/ydb/core/tablet_flat/benchmark/b_charge.cpp
index 3e862785b9..ece5e52034 100644
--- a/ydb/core/tablet_flat/benchmark/b_charge.cpp
+++ b/ydb/core/tablet_flat/benchmark/b_charge.cpp
@@ -1,8 +1,8 @@
 #include <benchmark/benchmark.h>
-#include <random>
 
 #include <ydb/core/tablet_flat/flat_row_celled.h>
-#include <ydb/core/tablet_flat/flat_part_charge.h>
+#include <ydb/core/tablet_flat/flat_part_charge_range.h>
+#include <ydb/core/tablet_flat/flat_part_charge_create.h>
 #include <ydb/core/tablet_flat/test/libs/rows/cook.h>
 #include <ydb/core/tablet_flat/test/libs/rows/tool.h>
 #include <ydb/core/tablet_flat/test/libs/table/model/large.h>
@@ -138,7 +138,7 @@ BENCHMARK_DEFINE_F(TModel, PrechargeByKeys)(benchmark::State& state) {
         const auto from = Tool.KeyCells(Mass.Saved[lower]);
         const auto to = Tool.KeyCells(Mass.Saved[upper]);
 
-        TCharge::Range(Env.Get(), from, to, *Run.Get(), keyDefaults, Tags, items, Max<ui64>());
+        ChargeRange(Env.Get(), from, to, *Run.Get(), keyDefaults, Tags, items, Max<ui64>());
     }
 
     state.counters["Touched"] = benchmark::Counter(Env->TouchedCount, benchmark::Counter::kAvgIterations);
@@ -154,7 +154,7 @@ BENCHMARK_DEFINE_F(TModel, PrechargeByRows)(benchmark::State& state) {
         ui32 lower = ++it % 50;
         ui32 upper = lower + items;
 
-        TCharge(Env.Get(), *(Run.Get())->begin()->Part, Tags, false).Do(lower, upper, keyDefaults, items, Max<ui64>());
+        CreateCharge(Env.Get(), *(Run.Get())->begin()->Part, Tags, false)->Do(lower, upper, keyDefaults, items, Max<ui64>());
     }
 
     state.counters["Touched"] = Env->TouchedCount / it;
diff --git a/ydb/core/tablet_flat/flat_part_charge.h b/ydb/core/tablet_flat/flat_part_charge.h
index 499e04c3ee..6e2531eec4 100644
--- a/ydb/core/tablet_flat/flat_part_charge.h
+++ b/ydb/core/tablet_flat/flat_part_charge.h
@@ -1,27 +1,20 @@
 #pragma once
 
-#include "defs.h"
 #include "flat_table_part.h"
 #include "flat_part_iface.h"
-#include "flat_part_slice.h"
 #include "flat_part_index_iter.h"
+#include "flat_part_charge_iface.h"
 
 #include <util/generic/bitmap.h>
 
 namespace NKikimr {
 namespace NTable {
 
-    class TCharge {
+    class TCharge : public ICharge {
     public:
-        using TCells = NPage::TCells;
         using TIter = NPage::TIndex::TIter;
         using TDataPage = NPage::TDataPage;
         using TGroupId = NPage::TGroupId;
-        
-        struct TResult {
-            bool Ready;     /* All required pages are already in memory */
-            bool Overshot;  /* Search may start outside of bounds */
-        };
 
         TCharge(IPages *env, const TPart &part, TTagsRef tags, bool includeHistory = false)
             : Env(env)
@@ -49,131 +42,8 @@ namespace NTable {
             }
         }
 
-        static bool Range(IPages *env, const TCells key1, const TCells key2,
-                    const TRun &run, const TKeyCellDefaults &keyDefaults, TTagsRef tags,
-                    ui64 items, ui64 bytes, bool includeHistory = false) noexcept
-        {
-            if (run.size() == 1) {
-                auto pos = run.begin();
-                TRowId row1 = pos->Slice.BeginRowId();
-                TRowId row2 = pos->Slice.EndRowId() - 1;
-                return TCharge(env, *pos->Part, tags, includeHistory).Do(key1, key2, row1, row2, keyDefaults, items, bytes).Ready;
-            }
-
-            bool ready = true;
-            auto pos = run.LowerBound(key1);
-
-            if (pos == run.end())
-                return true;
-
-            bool fromStart = TSlice::CompareSearchKeyFirstKey(key1, pos->Slice, keyDefaults) <= 0;
-
-            while (pos != run.end()) {
-                TRowId row1 = pos->Slice.BeginRowId();
-                TRowId row2 = pos->Slice.EndRowId() - 1;
-
-                const int cmp = TSlice::CompareLastKeySearchKey(pos->Slice, key2, keyDefaults);
-
-                TArrayRef<const TCell> key1r;
-                if (!fromStart) {
-                    key1r = key1;
-                }
-                TArrayRef<const TCell> key2r;
-                if (cmp > 0 /* slice->LastKey > key2 */) {
-                    key2r = key2;
-                }
-
-                auto r = TCharge(env, *pos->Part, tags, includeHistory).Do(key1r, key2r, row1, row2, keyDefaults, items, bytes);
-                ready &= r.Ready;
-
-                if (cmp >= 0 /* slice->LastKey >= key2 */) {
-                    if (r.Overshot && ++pos != run.end()) {
-                        // Unfortunately key > key2 might be at the start of the next slice
-                        TRowId firstRow = pos->Slice.BeginRowId();
-                        // Precharge the first row on the next slice
-                        TCharge(env, *pos->Part, tags, includeHistory).Do(firstRow, firstRow, keyDefaults, items, bytes);
-                    }
-
-                    break;
-                }
-
-                // Will consume this slice before encountering key2
-                fromStart = true;
-                ++pos;
-            }
-
-            return ready;
-        }
-
-        static bool RangeReverse(IPages *env, const TCells key1, const TCells key2,
-                    const TRun &run, const TKeyCellDefaults &keyDefaults, TTagsRef tags,
-                    ui64 items, ui64 bytes, bool includeHistory = false) noexcept
-        {
-            if (run.size() == 1) {
-                auto pos = run.begin();
-                TRowId row1 = pos->Slice.EndRowId() - 1;
-                TRowId row2 = pos->Slice.BeginRowId();
-                return TCharge(env, *pos->Part, tags, includeHistory).DoReverse(key1, key2, row1, row2, keyDefaults, items, bytes).Ready;
-            }
-
-            bool ready = true;
-            auto pos = run.LowerBoundReverse(key1);
-
-            if (pos == run.end())
-                return true;
-
-            bool fromEnd = TSlice::CompareLastKeySearchKey(pos->Slice, key1, keyDefaults) <= 0;
-
-            for (;;) {
-                TRowId row1 = pos->Slice.EndRowId() - 1;
-                TRowId row2 = pos->Slice.BeginRowId();
-
-                // N.B. empty key2 is like -inf during reverse iteration
-                const int cmp = key2 ? TSlice::CompareSearchKeyFirstKey(key2, pos->Slice, keyDefaults) : -1;
-
-                TArrayRef<const TCell> key1r;
-                if (!fromEnd) {
-                    key1r = key1;
-                }
-                TArrayRef<const TCell> key2r;
-                if (cmp > 0 /* key2 > slice->FirstKey */) {
-                    key2r = key2;
-                }
-
-                auto r = TCharge(env, *pos->Part, tags, includeHistory).DoReverse(key1r, key2r, row1, row2, keyDefaults, items, bytes);
-                ready &= r.Ready;
-
-                if (pos == run.begin()) {
-                    break;
-                }
-
-                if (cmp >= 0 /* key2 >= slice->FirstKey */) {
-                    if (r.Overshot) {
-                        --pos;
-                        // Unfortunately key <= key2 might be at the end of the previous slice
-                        TRowId lastRow = pos->Slice.EndRowId() - 1;
-                        // Precharge the last row on the previous slice
-                        TCharge(env, *pos->Part, tags, includeHistory).DoReverse(lastRow, lastRow, keyDefaults, items, bytes);
-                    }
-
-                    break;
-                }
-
-                // Will consume this slice before encountering key2
-                fromEnd = true;
-                --pos;
-            }
-
-            return ready;
-        }
-
-        /**
-         * Precharges data for rows between row1 and row2 inclusive
-         *
-         * Important caveat: assumes iteration won't touch any row > row2
-         */
         bool Do(const TRowId row1, const TRowId row2,
-                    const TKeyCellDefaults &keyDefaults, ui64 itemsLimit, ui64 bytesLimit) const noexcept
+                const TKeyCellDefaults &keyDefaults, ui64 itemsLimit, ui64 bytesLimit) const noexcept override
         {
             auto index = Index.TryLoadRaw();
             if (!index) {
@@ -199,13 +69,8 @@ namespace NTable {
             return DoPrecharge(TCells{}, TCells{}, TIter{}, TIter{}, first, last, startRow, endRow, keyDefaults, itemsLimit, bytesLimit);
         }
 
-        /**
-         * Precharges data for rows between row1 and row2 inclusive in reverse
-         *
-         * Important caveat: assumes iteration won't touch any row > row2
-         */
         bool DoReverse(const TRowId row1, const TRowId row2, 
-                const TKeyCellDefaults &keyDefaults, ui64 itemsLimit, ui64 bytesLimit) const noexcept
+                const TKeyCellDefaults &keyDefaults, ui64 itemsLimit, ui64 bytesLimit) const noexcept override
         {
             auto index = Index.TryLoadRaw();
             if (!index) {
@@ -236,12 +101,9 @@ namespace NTable {
             return DoPrechargeReverse(TCells{}, TCells{}, TIter{}, TIter{}, first, last, startRow, endRow, keyDefaults, itemsLimit, bytesLimit);
         }
 
-        /**
-         * Precharges data for rows between max(key1, row1) and min(key2, row2) inclusive
-         */
         TResult Do(const TCells key1, const TCells key2, const TRowId row1,
                 const TRowId row2, const TKeyCellDefaults &keyDefaults, ui64 itemsLimit,
-                ui64 bytesLimit) const noexcept
+                ui64 bytesLimit) const noexcept override
         {
             auto index = Index.TryLoadRaw();
             if (!index) {
@@ -307,12 +169,9 @@ namespace NTable {
             return { ready, overshot };
         }
 
-        /**
-         * Precharges data for rows between min(key1, row1) and max(key2, row2) inclusive in reverse
-         */
         TResult DoReverse(const TCells key1, const TCells key2, const TRowId row1,
                 const TRowId row2, const TKeyCellDefaults &keyDefaults, ui64 itemsLimit,
-                ui64 bytesLimit) const noexcept
+                ui64 bytesLimit) const noexcept override
         {
             auto index = Index.TryLoadRaw();
             if (!index) {
diff --git a/ydb/core/tablet_flat/flat_part_charge_btree_index.h b/ydb/core/tablet_flat/flat_part_charge_btree_index.h
new file mode 100644
index 0000000000..6a10a57cab
--- /dev/null
+++ b/ydb/core/tablet_flat/flat_part_charge_btree_index.h
@@ -0,0 +1,69 @@
+#pragma once
+
+#include "flat_table_part.h"
+#include "flat_part_iface.h"
+#include "flat_part_charge_iface.h"
+
+namespace NKikimr::NTable {
+
+    class TChargeBTreeIndex : public ICharge {
+    public:
+        TChargeBTreeIndex(IPages *env, const TPart &part, TTagsRef tags, bool includeHistory = false) {
+            Y_UNUSED(env);
+            Y_UNUSED(part);
+            Y_UNUSED(tags);
+            Y_UNUSED(includeHistory);
+        }
+
+        virtual bool Do(const TRowId row1, const TRowId row2,
+                const TKeyCellDefaults &keyDefaults, ui64 itemsLimit, ui64 bytesLimit) const noexcept override {
+            // TODO: implement
+            Y_UNUSED(row1);
+            Y_UNUSED(row2);
+            Y_UNUSED(keyDefaults);
+            Y_UNUSED(itemsLimit);
+            Y_UNUSED(bytesLimit);
+            return true;
+        }
+
+        virtual bool DoReverse(const TRowId row1, const TRowId row2, 
+                const TKeyCellDefaults &keyDefaults, ui64 itemsLimit, ui64 bytesLimit) const noexcept override {
+            // TODO: implement
+            Y_UNUSED(row1);
+            Y_UNUSED(row2);
+            Y_UNUSED(keyDefaults);
+            Y_UNUSED(itemsLimit);
+            Y_UNUSED(bytesLimit);
+            return true;
+        }
+
+        virtual TResult Do(const TCells key1, const TCells key2, const TRowId row1,
+                const TRowId row2, const TKeyCellDefaults &keyDefaults, ui64 itemsLimit,
+                ui64 bytesLimit) const noexcept override {
+            // TODO: implement
+            Y_UNUSED(key1);
+            Y_UNUSED(key2);
+            Y_UNUSED(row1);
+            Y_UNUSED(row2);
+            Y_UNUSED(keyDefaults);
+            Y_UNUSED(itemsLimit);
+            Y_UNUSED(bytesLimit);
+            return {true, false};
+        }
+
+        virtual TResult DoReverse(const TCells key1, const TCells key2, const TRowId row1,
+                const TRowId row2, const TKeyCellDefaults &keyDefaults, ui64 itemsLimit,
+                ui64 bytesLimit) const noexcept override {
+            // TODO: implement
+            Y_UNUSED(key1);
+            Y_UNUSED(key2);
+            Y_UNUSED(row1);
+            Y_UNUSED(row2);
+            Y_UNUSED(keyDefaults);
+            Y_UNUSED(itemsLimit);
+            Y_UNUSED(bytesLimit);
+            return {true, false};
+        }
+};
+
+}
diff --git a/ydb/core/tablet_flat/flat_part_charge_create.cpp b/ydb/core/tablet_flat/flat_part_charge_create.cpp
new file mode 100644
index 0000000000..30b9a52547
--- /dev/null
+++ b/ydb/core/tablet_flat/flat_part_charge_create.cpp
@@ -0,0 +1,15 @@
+#include "flat_part_charge_create.h"
+#include "flat_part_charge.h"
+#include "flat_part_charge_btree_index.h"
+
+namespace NKikimr::NTable {
+
+THolder<ICharge> CreateCharge(IPages *env, const TPart &part, TTagsRef tags, bool includeHistory) {
+    if (part.IndexPages.BTreeGroups) {
+        return MakeHolder<TChargeBTreeIndex>(env, part, tags, includeHistory);
+    } else {
+        return MakeHolder<TCharge>(env, part, tags, includeHistory);
+    }
+}
+
+}
diff --git a/ydb/core/tablet_flat/flat_part_charge_create.h b/ydb/core/tablet_flat/flat_part_charge_create.h
new file mode 100644
index 0000000000..40249e631f
--- /dev/null
+++ b/ydb/core/tablet_flat/flat_part_charge_create.h
@@ -0,0 +1,10 @@
+#pragma once
+
+#include "flat_part_charge_iface.h"
+#include "flat_part_iface.h"
+
+namespace NKikimr::NTable {
+
+THolder<ICharge> CreateCharge(IPages *env, const TPart &part, TTagsRef tags, bool includeHistory = false);
+
+}
diff --git a/ydb/core/tablet_flat/flat_part_charge_iface.h b/ydb/core/tablet_flat/flat_part_charge_iface.h
new file mode 100644
index 0000000000..698e927262
--- /dev/null
+++ b/ydb/core/tablet_flat/flat_part_charge_iface.h
@@ -0,0 +1,48 @@
+#pragma once
+
+#include "flat_page_base.h"
+
+namespace NKikimr::NTable {
+
+    struct ICharge {
+        using TCells = NPage::TCells;
+
+        struct TResult {
+            bool Ready;     /* All required pages are already in memory */
+            bool Overshot;  /* Search may start outside of bounds */
+        };
+
+        /**
+         * Precharges data for rows between row1 and row2 inclusive
+         *
+         * Important caveat: assumes iteration won't touch any row > row2
+         */
+        virtual bool Do(const TRowId row1, const TRowId row2,
+                const TKeyCellDefaults &keyDefaults, ui64 itemsLimit, ui64 bytesLimit) const noexcept = 0;
+
+        /**
+         * Precharges data for rows between row1 and row2 inclusive in reverse
+         *
+         * Important caveat: assumes iteration won't touch any row > row2
+         */
+        virtual bool DoReverse(const TRowId row1, const TRowId row2, 
+                const TKeyCellDefaults &keyDefaults, ui64 itemsLimit, ui64 bytesLimit) const noexcept = 0;
+
+        /**
+         * Precharges data for rows between max(key1, row1) and min(key2, row2) inclusive
+         */
+        virtual TResult Do(const TCells key1, const TCells key2, const TRowId row1,
+                const TRowId row2, const TKeyCellDefaults &keyDefaults, ui64 itemsLimit,
+                ui64 bytesLimit) const noexcept = 0;
+
+        /**
+         * Precharges data for rows between min(key1, row1) and max(key2, row2) inclusive in reverse
+         */
+        virtual TResult DoReverse(const TCells key1, const TCells key2, const TRowId row1,
+                const TRowId row2, const TKeyCellDefaults &keyDefaults, ui64 itemsLimit,
+                ui64 bytesLimit) const noexcept = 0;
+
+        virtual ~ICharge() = default;
+};
+
+}
diff --git a/ydb/core/tablet_flat/flat_part_charge_range.cpp b/ydb/core/tablet_flat/flat_part_charge_range.cpp
new file mode 100644
index 0000000000..3ba7325fca
--- /dev/null
+++ b/ydb/core/tablet_flat/flat_part_charge_range.cpp
@@ -0,0 +1,124 @@
+#include "flat_part_charge_range.h"
+#include "flat_part_charge_create.h"
+
+namespace NKikimr::NTable {
+
+bool ChargeRange(IPages *env, const TCells key1, const TCells key2,
+            const TRun &run, const TKeyCellDefaults &keyDefaults, TTagsRef tags,
+            ui64 items, ui64 bytes, bool includeHistory) noexcept
+{
+    if (run.size() == 1) {
+        auto pos = run.begin();
+        TRowId row1 = pos->Slice.BeginRowId();
+        TRowId row2 = pos->Slice.EndRowId() - 1;
+        return CreateCharge(env, *pos->Part, tags, includeHistory)->Do(key1, key2, row1, row2, keyDefaults, items, bytes).Ready;
+    }
+
+    bool ready = true;
+    auto pos = run.LowerBound(key1);
+
+    if (pos == run.end())
+        return true;
+
+    bool fromStart = TSlice::CompareSearchKeyFirstKey(key1, pos->Slice, keyDefaults) <= 0;
+
+    while (pos != run.end()) {
+        TRowId row1 = pos->Slice.BeginRowId();
+        TRowId row2 = pos->Slice.EndRowId() - 1;
+
+        const int cmp = TSlice::CompareLastKeySearchKey(pos->Slice, key2, keyDefaults);
+
+        TArrayRef<const TCell> key1r;
+        if (!fromStart) {
+            key1r = key1;
+        }
+        TArrayRef<const TCell> key2r;
+        if (cmp > 0 /* slice->LastKey > key2 */) {
+            key2r = key2;
+        }
+
+        auto r = CreateCharge(env, *pos->Part, tags, includeHistory)->Do(key1r, key2r, row1, row2, keyDefaults, items, bytes);
+        ready &= r.Ready;
+
+        if (cmp >= 0 /* slice->LastKey >= key2 */) {
+            if (r.Overshot && ++pos != run.end()) {
+                // Unfortunately key > key2 might be at the start of the next slice
+                TRowId firstRow = pos->Slice.BeginRowId();
+                // Precharge the first row on the next slice
+                CreateCharge(env, *pos->Part, tags, includeHistory)->Do(firstRow, firstRow, keyDefaults, items, bytes);
+            }
+
+            break;
+        }
+
+        // Will consume this slice before encountering key2
+        fromStart = true;
+        ++pos;
+    }
+
+    return ready;
+}
+
+bool ChargeRangeReverse(IPages *env, const TCells key1, const TCells key2,
+            const TRun &run, const TKeyCellDefaults &keyDefaults, TTagsRef tags,
+            ui64 items, ui64 bytes, bool includeHistory) noexcept
+{
+    if (run.size() == 1) {
+        auto pos = run.begin();
+        TRowId row1 = pos->Slice.EndRowId() - 1;
+        TRowId row2 = pos->Slice.BeginRowId();
+        return CreateCharge(env, *pos->Part, tags, includeHistory)->DoReverse(key1, key2, row1, row2, keyDefaults, items, bytes).Ready;
+    }
+
+    bool ready = true;
+    auto pos = run.LowerBoundReverse(key1);
+
+    if (pos == run.end())
+        return true;
+
+    bool fromEnd = TSlice::CompareLastKeySearchKey(pos->Slice, key1, keyDefaults) <= 0;
+
+    for (;;) {
+        TRowId row1 = pos->Slice.EndRowId() - 1;
+        TRowId row2 = pos->Slice.BeginRowId();
+
+        // N.B. empty key2 is like -inf during reverse iteration
+        const int cmp = key2 ? TSlice::CompareSearchKeyFirstKey(key2, pos->Slice, keyDefaults) : -1;
+
+        TArrayRef<const TCell> key1r;
+        if (!fromEnd) {
+            key1r = key1;
+        }
+        TArrayRef<const TCell> key2r;
+        if (cmp > 0 /* key2 > slice->FirstKey */) {
+            key2r = key2;
+        }
+
+        auto r = CreateCharge(env, *pos->Part, tags, includeHistory)->DoReverse(key1r, key2r, row1, row2, keyDefaults, items, bytes);
+        ready &= r.Ready;
+
+        if (pos == run.begin()) {
+            break;
+        }
+
+        if (cmp >= 0 /* key2 >= slice->FirstKey */) {
+            if (r.Overshot) {
+                --pos;
+                // Unfortunately key <= key2 might be at the end of the previous slice
+                TRowId lastRow = pos->Slice.EndRowId() - 1;
+                // Precharge the last row on the previous slice
+                CreateCharge(env, *pos->Part, tags, includeHistory)->DoReverse(lastRow, lastRow, keyDefaults, items, bytes);
+            }
+
+            break;
+        }
+
+        // Will consume this slice before encountering key2
+        fromEnd = true;
+        --pos;
+    }
+
+    return ready;
+}
+
+}
diff --git a/ydb/core/tablet_flat/flat_part_charge_range.h b/ydb/core/tablet_flat/flat_part_charge_range.h
new file mode 100644
index 0000000000..88b921fc00
--- /dev/null
+++ b/ydb/core/tablet_flat/flat_part_charge_range.h
@@ -0,0 +1,20 @@
+#pragma once
+
+#include "flat_part_iface.h"
+#include "flat_part_slice.h"
+
+namespace NKikimr::NTable {
+
+namespace {
+    using TCells = NPage::TCells;
+}
+
+bool ChargeRange(IPages *env, const TCells key1, const TCells key2,
+            const TRun &run, const TKeyCellDefaults &keyDefaults, TTagsRef tags,
+            ui64 items, ui64 bytes, bool includeHistory = false) noexcept;
+
+bool ChargeRangeReverse(IPages *env, const TCells key1, const TCells key2,
+            const TRun &run, const TKeyCellDefaults &keyDefaults, TTagsRef tags,
+            ui64 items, ui64 bytes, bool includeHistory = false) noexcept;
+
+}
diff --git a/ydb/core/tablet_flat/flat_table.cpp b/ydb/core/tablet_flat/flat_table.cpp
index 66fcbecea3..e3feb7e3ea 100644
--- a/ydb/core/tablet_flat/flat_table.cpp
+++ b/ydb/core/tablet_flat/flat_table.cpp
@@ -4,8 +4,8 @@
 #include "flat_bloom_hash.h"
 #include "flat_part_iter_multi.h"
 #include "flat_part_laid.h"
-#include "flat_part_shrink.h"
-#include "flat_part_charge.h"
+#include "flat_part_charge_range.h"
+#include "flat_part_charge_create.h"
 #include "flat_part_dump.h"
 #include "flat_range_cache.h"
 #include "flat_util_misc.h"
@@ -789,8 +789,8 @@ EReady TTable::Precharge(TRawVals minKey_, TRawVals maxKey_, TTagsRef tags,
                 {
                     TRowId row1 = pos->Slice.BeginRowId();
                     TRowId row2 = pos->Slice.EndRowId() - 1;
-                    ready &= TCharge(env, *pos->Part, tags, includeHistory)
-                        .Do(key, key, row1, row2, *Scheme->Keys, items, bytes)
+                    ready &= CreateCharge(env, *pos->Part, tags, includeHistory)
+                        ->Do(key, key, row1, row2, *Scheme->Keys, items, bytes)
                         .Ready;
                     ++stats.Sieved;
                 } else {
@@ -805,10 +805,10 @@ EReady TTable::Precharge(TRawVals minKey_, TRawVals maxKey_, TTagsRef tags,
         for (const auto& run : GetLevels()) {
             switch (direction) {
                 case EDirection::Forward:
-                    ready &= TCharge::Range(env, minKey, maxKey, run, *Scheme->Keys, tags, items, bytes, includeHistory);
+                    ready &= ChargeRange(env, minKey, maxKey, run, *Scheme->Keys, tags, items, bytes, includeHistory);
                     break;
                 case EDirection::Reverse:
-                    ready &= TCharge::RangeReverse(env, maxKey, minKey, run, *Scheme->Keys, tags, items, bytes, includeHistory);
+                    ready &= ChargeRangeReverse(env, maxKey, minKey, run, *Scheme->Keys, tags, items, bytes, includeHistory);
                     break;
             }
         }
diff --git a/ydb/core/tablet_flat/ut/ut_charge.cpp b/ydb/core/tablet_flat/ut/ut_charge.cpp
index aea20ce174..195577ffc7 100644
--- a/ydb/core/tablet_flat/ut/ut_charge.cpp
+++ b/ydb/core/tablet_flat/ut/ut_charge.cpp
@@ -1,5 +1,6 @@
 #include <ydb/core/tablet_flat/flat_row_celled.h>
-#include <ydb/core/tablet_flat/flat_part_charge.h>
+#include <ydb/core/tablet_flat/flat_part_charge_range.h>
+#include <ydb/core/tablet_flat/flat_part_charge_create.h>
 #include <ydb/core/tablet_flat/test/libs/rows/cook.h>
 #include <ydb/core/tablet_flat/test/libs/rows/tool.h>
 #include <ydb/core/tablet_flat/test/libs/table/model/large.h>
@@ -196,10 +197,10 @@ namespace {
             }
 
             bool ready = !reverse
-                ? TCharge::Range(&env, from, to, run, keyDefaults, tags, items, Max<ui64>(), true)
-                : TCharge::RangeReverse(&env, from, to, run, keyDefaults, tags, items, Max<ui64>(), true);
+                ? ChargeRange(&env, from, to, run, keyDefaults, tags, items, Max<ui64>(), true)
+                : ChargeRangeReverse(&env, from, to, run, keyDefaults, tags, items, Max<ui64>(), true);
 
-            UNIT_ASSERT_VALUES_EQUAL_C(!fail || env.ToLoad.empty(), ready, AssertMesage(fail));
+            UNIT_ASSERT_VALUES_EQUAL_C(!fail || env.ToLoad.empty(), ready, AssertMessage(fail));
 
             CheckPrecharged(env.Touched, shouldPrecharge, sticky, flags);
         }
@@ -226,8 +227,8 @@ namespace {
 
             UNIT_ASSERT_VALUES_EQUAL_C(
                 !fail,
-                TCharge(&env, *run.begin()->Part, tags, false).Do(row1, row2, keyDefaults, items, Max<ui64>()),
-                AssertMesage(fail));
+                CreateCharge(&env, *run.begin()->Part, tags, false)->Do(row1, row2, keyDefaults, items, Max<ui64>()),
+                AssertMessage(fail));
 
             CheckPrecharged(env.Touched, shouldPrecharge, sticky, fail ? TPageIdFlags::IfFail : TPageIdFlags::IfNoFail);
         }
@@ -361,7 +362,7 @@ namespace {
             }
         }
 
-        std::string AssertMesage(bool fail) const {
+        std::string AssertMessage(bool fail) const {
             return 
                 "Seq: " + std::to_string(CurrentStep()) + 
                 " Fail: " + (fail ? "Yes" : "No");
diff --git a/ydb/core/tablet_flat/ut/ut_part.cpp b/ydb/core/tablet_flat/ut/ut_part.cpp
index 3de1b3e3d9..9be2c73329 100644
--- a/ydb/core/tablet_flat/ut/ut_part.cpp
+++ b/ydb/core/tablet_flat/ut/ut_part.cpp
@@ -1,5 +1,5 @@
-#include "flat_part_charge.h"
 #include <ydb/core/tablet_flat/flat_part_dump.h>
+#include "ydb/core/tablet_flat/flat_part_charge_range.h"
 #include <ydb/core/tablet_flat/test/libs/rows/cook.h>
 #include <ydb/core/tablet_flat/test/libs/rows/layout.h>
 #include <ydb/core/tablet_flat/test/libs/table/model/large.h>
@@ -97,9 +97,9 @@ namespace {
         }
 
         if constexpr (Direction == EDirection::Forward) {
-            TCharge::Range(env, from, to, run, *keyDefaults, tags, 0, 0, true);
+            ChargeRange(env, from, to, run, *keyDefaults, tags, 0, 0, true);
         } else {
-            TCharge::RangeReverse(env, from, to, run, *keyDefaults, tags, 0, 0, true);
+            ChargeRangeReverse(env, from, to, run, *keyDefaults, tags, 0, 0, true);
         }
 
         env->PrechargePhase = false;
diff --git a/ydb/core/tablet_flat/ya.make b/ydb/core/tablet_flat/ya.make
index bb186aa53e..8a6604935e 100644
--- a/ydb/core/tablet_flat/ya.make
+++ b/ydb/core/tablet_flat/ya.make
@@ -41,6 +41,8 @@ SRCS(
     flat_sausagecache.cpp
     flat_sausagecache.h
     flat_sausage_meta.cpp
+    flat_part_charge_create.cpp
+    flat_part_charge_range.cpp
     flat_page_label.cpp
     flat_part_dump.cpp
     flat_part_iter_multi.cpp