KIKIMR-19521 BTreeIndex Keep B-TreeIndex in cache after compactions (#1165)

2 files changed, 50 insertions, 2 deletions

diff --git a/ydb/core/tablet_flat/flat_executor_ut.cpp b/ydb/core/tablet_flat/flat_executor_ut.cpp
index 89e2a69fd9a..18d8399728b 100644
--- a/ydb/core/tablet_flat/flat_executor_ut.cpp
+++ b/ydb/core/tablet_flat/flat_executor_ut.cpp
@@ -5569,6 +5569,53 @@ Y_UNIT_TEST_SUITE(TFlatTableExecutorBTreeIndex) {
         UNIT_ASSERT_VALUES_EQUAL(failedAttempts, 288);
     }
 
+    Y_UNIT_TEST(UseBtreeIndex_True_Generations) {
+        TMyEnvBase env;
+        TRowsModel rows;
+
+        auto &appData = env->GetAppData();
+        appData.FeatureFlags.SetEnableLocalDBBtreeIndex(true);
+        auto counters = MakeIntrusive<TSharedPageCacheCounters>(env->GetDynamicCounters());
+        int readRows = 0, failedAttempts = 0;
+
+        env.FireDummyTablet(ui32(NFake::TDummy::EFlg::Comp));
+
+        auto policy = MakeIntrusive<TCompactionPolicy>();
+        policy->MinBTreeIndexNodeSize = 128;
+        policy->Generations.push_back({100 * 1024, 2, 2, 200 * 1024, NLocalDb::LegacyQueueIdToTaskName(1), false});
+        for (auto& gen : policy->Generations) {
+            gen.ExtraCompactionPercent = 0;
+            gen.ExtraCompactionMinSize = 0;
+            gen.ExtraCompactionExpPercent = 0;
+            gen.ExtraCompactionExpMaxSize = 0;
+            gen.UpliftPartSize = 0;
+        }
+        env.SendSync(rows.MakeScheme(std::move(policy)));
+
+        env.SendSync(rows.VersionTo(TRowVersion(1, 10)).RowTo(0).MakeRows(1000, 950));
+        env.SendSync(rows.VersionTo(TRowVersion(2, 20)).RowTo(0).MakeRows(1000, 950));
+
+        env.SendSync(new NFake::TEvCompact(TRowsModel::TableId));
+        env.WaitFor<NFake::TEvCompacted>();
+
+        // gen 0 data pages are always kept in shared cache
+        // b-tree index pages are always kept in shared cache
+        UNIT_ASSERT_VALUES_EQUAL(counters->ActivePages->Val(), 48);
+
+        env.SendSync(new NFake::TEvExecute{ new TTxFullScan(readRows, failedAttempts) });
+        UNIT_ASSERT_VALUES_EQUAL(readRows, 1000);
+        UNIT_ASSERT_VALUES_EQUAL(failedAttempts, 286);
+
+        // restart tablet
+        env.SendSync(new TEvents::TEvPoison, false, true);
+        env.FireDummyTablet(ui32(NFake::TDummy::EFlg::Comp));
+
+        // after restart we have no pages in private cache
+        env.SendSync(new NFake::TEvExecute{ new TTxFullScan(readRows, failedAttempts) }, true);
+        UNIT_ASSERT_VALUES_EQUAL(readRows, 1000);
+        UNIT_ASSERT_VALUES_EQUAL(failedAttempts, 332);
+    }
+
 }
 
 } // namespace NTabletFlatExecutor
diff --git a/ydb/core/tablet_flat/flat_writer_blocks.h b/ydb/core/tablet_flat/flat_writer_blocks.h
index 2b123e4f53d..76cd0f6fe8b 100644
--- a/ydb/core/tablet_flat/flat_writer_blocks.h
+++ b/ydb/core/tablet_flat/flat_writer_blocks.h
@@ -61,10 +61,11 @@ namespace NWriter {
             for (auto &glob : Writer.Grab())
                 Cone->Put(std::move(glob));
 
-            // Note: we mark flat index pages sticky after we load them
             if (NTable::TLoader::NeedIn(type) || StickyFlatIndex && type == EPage::Index) {
+                // Note: we mark flat index pages sticky after we load them
                 Sticky.emplace_back(pageId, std::move(raw));
-            } else if (bool(Cache) && (type == EPage::DataPage || type == EPage::BTreeIndex)) {
+            } else if (bool(Cache) && type == EPage::DataPage || type == EPage::BTreeIndex) {
+                // Note: we save b-tree index pages to shared cache regardless of a cache mode  
                 Regular.emplace_back(pageId, std::move(raw));
             }