check begin

Author: kungasc

ydb/core/tablet_flat/flat_fwd_cache.h

@@ -279,7 +279,7 @@ namespace NFwd {
             TDeque<TPageEx> Pages;
             ui32 PagesBeginOffset = 0, PagesPendingOffset = 0;
             TDeque<TNodeState> Queue;
-            TPageId EndPageId = 0;
+            TPageId BeginPageId = Max<TPageId>(), EndPageId = 0;
         };
 
     public:
@@ -301,6 +301,7 @@ namespace NFwd {
             auto& meta = Part->IndexPages.GetBTree(groupId);
             Levels.resize(meta.LevelCount + 1);
             Levels[0].Queue.push_back({meta.GetPageId(), meta.GetDataSize()});
+            Levels[0].BeginPageId = 0;
             Levels[0].EndPageId = meta.GetPageId() + 1;
             if (meta.LevelCount) {
                 IndexPageLocator.Add(meta.GetPageId(), GroupId, 0);
@@ -320,8 +321,8 @@ namespace NFwd {
                 return {page, false, true};
             }
 
-            Y_ENSURE(pageId < level.EndPageId, "Requested page " << pageId << " is out of loaded slice "
-                << BeginRowId << " " << EndRowId << " " << level.EndPageId << " with index " << Part->IndexPages.GetBTree(GroupId).ToString());
+            Y_ENSURE(level.BeginPageId <= pageId && pageId < level.EndPageId, "Requested page " << pageId << " is out of loaded slice "
+                << BeginRowId << " " << EndRowId << " " << level.BeginPageId << " " << level.EndPageId << " with index " << Part->IndexPages.GetBTree(GroupId).ToString());
 
             DropPagesBefore(level, pageId);
             ShrinkPages(level);
@@ -437,6 +438,9 @@ namespace NFwd {
                         auto& nextLevel = Levels[levelId + 1];
                         Y_ENSURE(!nextLevel.Queue || nextLevel.Queue.back().PageId < child.GetPageId());
                         nextLevel.Queue.push_back({child.GetPageId(), child.GetDataSize()});
+                        if (nextLevel.BeginPageId == Max<TPageId>()) {
+                            nextLevel.BeginPageId = child.GetPageId();
+                        }
                         nextLevel.EndPageId = child.GetPageId() + 1;
                         if (child.GetRowCount() >= EndRowId) {
                             break;

ydb/core/tablet_flat/ut/ut_btree_index_iter_charge.cpp

@@ -108,7 +108,7 @@ namespace {
             Type7,
             // new types should go here
 
-            UpperLoopLimit
+            End
         };
 
         const ui32 Levels = Max<ui32>();
@@ -1074,7 +1074,7 @@ Y_UNIT_TEST_SUITE(TPartBtreeIndexIteration) {
     }
 
     Y_UNIT_TEST(OneNode_Slices) {
-        for (auto slices : xrange<ui32>(TTestParams::ESlices::None + 1, TTestParams::ESlices::UpperLoopLimit)) {
+        for (auto slices : xrange<ui32>(TTestParams::ESlices::None + 1, TTestParams::ESlices::End)) {
             CheckPart({.Levels = 1, .Slices = TTestParams::ESlices(slices)});
         }
     }
@@ -1114,7 +1114,7 @@ Y_UNIT_TEST_SUITE(TPartBtreeIndexIteration) {
     }
 
     Y_UNIT_TEST(FewNodes_Slices) {
-        for (auto slices : xrange<ui32>(TTestParams::ESlices::None + 1, TTestParams::ESlices::UpperLoopLimit)) {
+        for (auto slices : xrange<ui32>(TTestParams::ESlices::None + 1, TTestParams::ESlices::End)) {
             CheckPart({.Levels = 3, .Slices = TTestParams::ESlices(slices)});
         }
     }