Lock index impl tables before scanning them (#17229)

13 files changed, 339 insertions, 120 deletions

diff --git a/ydb/core/kqp/ut/indexes/kqp_indexes_ut.cpp b/ydb/core/kqp/ut/indexes/kqp_indexes_ut.cpp
index 248c9ebb9b4..bcddfee4385 100644
--- a/ydb/core/kqp/ut/indexes/kqp_indexes_ut.cpp
+++ b/ydb/core/kqp/ut/indexes/kqp_indexes_ut.cpp
@@ -119,6 +119,8 @@ Y_UNIT_TEST_SUITE(KqpIndexMetadata) {
             .SetKqpSettings({setting});
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
 
         auto& server = kikimr.GetTestServer();
         auto gateway = GetIcGateway(server);
@@ -275,6 +277,8 @@ Y_UNIT_TEST_SUITE(KqpIndexMetadata) {
             .SetKqpSettings({setting});
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
 
         auto& server = kikimr.GetTestServer();
         auto gateway = GetIcGateway(server);
@@ -389,6 +393,8 @@ Y_UNIT_TEST_SUITE(KqpIndexes) {
             .SetKqpSettings({setting});
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
         auto db = kikimr.GetTableClient();
         auto session = db.CreateSession().GetValueSync().GetSession();
 
@@ -447,6 +453,8 @@ Y_UNIT_TEST_SUITE(KqpIndexes) {
             .SetKqpSettings({setting});
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
         auto db = kikimr.GetTableClient();
         auto session = db.CreateSession().GetValueSync().GetSession();
 
@@ -527,6 +535,8 @@ Y_UNIT_TEST_SUITE(KqpIndexes) {
             .SetKqpSettings({setting});
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
         auto db = kikimr.GetTableClient();
         auto session = db.CreateSession().GetValueSync().GetSession();
 
@@ -607,6 +617,8 @@ Y_UNIT_TEST_SUITE(KqpIndexes) {
             .SetKqpSettings({setting});
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
         auto db = kikimr.GetTableClient();
         auto session = db.CreateSession().GetValueSync().GetSession();
 
@@ -792,6 +804,8 @@ Y_UNIT_TEST_SUITE(KqpIndexes) {
             .SetKqpSettings({setting});
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
         auto db = kikimr.GetTableClient();
         auto session = db.CreateSession().GetValueSync().GetSession();
 
@@ -915,6 +929,8 @@ Y_UNIT_TEST_SUITE(KqpIndexes) {
             .SetAppConfig(appConfig);
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
         auto db = kikimr.GetTableClient();
         auto session = db.CreateSession().GetValueSync().GetSession();
 
@@ -1047,6 +1063,8 @@ Y_UNIT_TEST_SUITE(KqpIndexes) {
             .SetAppConfig(appConfig);
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
         auto db = kikimr.GetTableClient();
         auto session = db.CreateSession().GetValueSync().GetSession();
 
@@ -1282,6 +1300,8 @@ Y_UNIT_TEST_SUITE(KqpIndexes) {
             .SetKqpSettings({ setting });
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
         auto db = kikimr.GetTableClient();
         auto session = db.CreateSession().GetValueSync().GetSession();
 
@@ -1377,6 +1397,8 @@ Y_UNIT_TEST_SUITE(KqpIndexes) {
             .SetKqpSettings({setting});
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
         auto db = kikimr.GetTableClient();
         auto session = db.CreateSession().GetValueSync().GetSession();
 
@@ -1514,6 +1536,8 @@ Y_UNIT_TEST_SUITE(KqpIndexes) {
             .SetKqpSettings({setting});
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
         auto db = kikimr.GetTableClient();
         auto session = db.CreateSession().GetValueSync().GetSession();
 
@@ -1707,6 +1731,8 @@ Y_UNIT_TEST_SUITE(KqpIndexes) {
             .SetKqpSettings({setting});
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
         auto db = kikimr.GetTableClient();
         auto session = db.CreateSession().GetValueSync().GetSession();
 
@@ -1797,6 +1823,8 @@ Y_UNIT_TEST_SUITE(KqpIndexes) {
             .SetKqpSettings({setting});
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
         auto db = kikimr.GetTableClient();
         auto session = db.CreateSession().GetValueSync().GetSession();
 
@@ -1863,6 +1891,8 @@ Y_UNIT_TEST_SUITE(KqpIndexes) {
             .SetKqpSettings({setting});
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
         auto db = kikimr.GetTableClient();
         TScriptingClient client(kikimr.GetDriver());
         {
@@ -1904,6 +1934,8 @@ Y_UNIT_TEST_SUITE(KqpIndexes) {
 
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
         auto db = kikimr.GetTableClient();
         auto session = db.CreateSession().GetValueSync().GetSession();
 
@@ -2382,6 +2414,8 @@ Y_UNIT_TEST_SUITE(KqpIndexes) {
 
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
         auto db = kikimr.GetTableClient();
         auto session = DoCreateTableForVectorIndex(db, false);
         {
@@ -2425,6 +2459,8 @@ Y_UNIT_TEST_SUITE(KqpIndexes) {
 
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
         auto db = kikimr.GetTableClient();
         auto session = DoCreateTableForVectorIndex(db, false);
         {
@@ -2468,6 +2504,8 @@ Y_UNIT_TEST_SUITE(KqpIndexes) {
 
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
         auto db = kikimr.GetTableClient();
         auto session = DoCreateTableForVectorIndex(db, true);
         {
@@ -2511,6 +2549,8 @@ Y_UNIT_TEST_SUITE(KqpIndexes) {
 
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
         auto db = kikimr.GetTableClient();
         auto session = DoCreateTableForVectorIndex(db, true);
         {
@@ -2554,6 +2594,8 @@ Y_UNIT_TEST_SUITE(KqpIndexes) {
 
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
         auto db = kikimr.GetTableClient();
         auto session = DoCreateTableForVectorIndex(db, false);
         {
@@ -2597,6 +2639,8 @@ Y_UNIT_TEST_SUITE(KqpIndexes) {
 
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
         auto db = kikimr.GetTableClient();
         auto session = DoCreateTableForVectorIndex(db, false);
         {
@@ -2640,6 +2684,8 @@ Y_UNIT_TEST_SUITE(KqpIndexes) {
 
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
         auto db = kikimr.GetTableClient();
         auto session = DoCreateTableForVectorIndex(db, true);
         {
@@ -2683,6 +2729,8 @@ Y_UNIT_TEST_SUITE(KqpIndexes) {
 
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
         auto db = kikimr.GetTableClient();
         auto session = DoCreateTableForVectorIndex(db, true);
         {
@@ -2716,6 +2764,52 @@ Y_UNIT_TEST_SUITE(KqpIndexes) {
         DoPositiveQueriesVectorIndexOrderByCosine(session);
     }
 
+    Y_UNIT_TEST(SimpleVectorIndexOrderByCosineDistanceNotNullableLevel3) {
+        NKikimrConfig::TFeatureFlags featureFlags;
+        featureFlags.SetEnableVectorIndex(true);
+        auto setting = NKikimrKqp::TKqpSetting();
+        auto serverSettings = TKikimrSettings()
+            .SetFeatureFlags(featureFlags)
+            .SetKqpSettings({setting});
+
+        TKikimrRunner kikimr(serverSettings);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
+        auto db = kikimr.GetTableClient();
+        auto session = DoCreateTableForVectorIndex(db, false);
+        {
+            const TString createIndex(Q_(R"(
+                ALTER TABLE `/Root/TestTable`
+                    ADD INDEX index
+                    GLOBAL USING vector_kmeans_tree
+                    ON (emb)
+                    WITH (distance=cosine, vector_type="uint8", vector_dimension=2, levels=3, clusters=2);
+            )"));
+
+            auto result = session.ExecuteSchemeQuery(createIndex)
+                          .ExtractValueSync();
+
+            UNIT_ASSERT_C(result.IsSuccess(), result.GetIssues().ToString());
+        }
+        {
+            auto result = session.DescribeTable("/Root/TestTable").ExtractValueSync();
+            UNIT_ASSERT_VALUES_EQUAL(result.GetStatus(), NYdb::EStatus::SUCCESS);
+            const auto& indexes = result.GetTableDescription().GetIndexDescriptions();
+            UNIT_ASSERT_EQUAL(indexes.size(), 1);
+            UNIT_ASSERT_EQUAL(indexes[0].GetIndexName(), "index");
+            UNIT_ASSERT_EQUAL(indexes[0].GetIndexColumns(), std::vector<std::string>{"emb"});
+            const auto& settings = std::get<TKMeansTreeSettings>(indexes[0].GetIndexSettings());
+            UNIT_ASSERT_EQUAL(settings.Settings.Metric, NYdb::NTable::TVectorIndexSettings::EMetric::CosineDistance);
+            UNIT_ASSERT_EQUAL(settings.Settings.VectorType, NYdb::NTable::TVectorIndexSettings::EVectorType::Uint8);
+            UNIT_ASSERT_EQUAL(settings.Settings.VectorDimension, 2);
+            UNIT_ASSERT_EQUAL(settings.Levels, 3);
+            UNIT_ASSERT_EQUAL(settings.Clusters, 2);
+        }
+        // TODO: fix somehow?
+        // DoPositiveQueriesVectorIndexOrderByCosine(session);
+    }
+
     void DoPositiveQueriesPrefixedVectorIndexOrderBy(
         TSession& session,
         std::string_view function,
@@ -2888,6 +2982,8 @@ Y_UNIT_TEST_SUITE(KqpIndexes) {
 
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
 
         auto db = kikimr.GetTableClient();
         auto session = DoCreateTableForPrefixedVectorIndex(db, false);
@@ -2933,6 +3029,8 @@ Y_UNIT_TEST_SUITE(KqpIndexes) {
 
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
 
         auto db = kikimr.GetTableClient();
         auto session = DoCreateTableForPrefixedVectorIndex(db, false);
@@ -2978,6 +3076,8 @@ Y_UNIT_TEST_SUITE(KqpIndexes) {
 
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
 
         auto db = kikimr.GetTableClient();
         auto session = DoCreateTableForPrefixedVectorIndex(db, true);
@@ -3023,6 +3123,8 @@ Y_UNIT_TEST_SUITE(KqpIndexes) {
 
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
 
         auto db = kikimr.GetTableClient();
         auto session = DoCreateTableForPrefixedVectorIndex(db, true);
@@ -3068,6 +3170,8 @@ Y_UNIT_TEST_SUITE(KqpIndexes) {
 
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
 
         auto db = kikimr.GetTableClient();
         auto session = DoCreateTableForPrefixedVectorIndex(db, false);
@@ -3205,6 +3309,8 @@ Y_UNIT_TEST_SUITE(KqpIndexes) {
 
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
 
         auto db = kikimr.GetTableClient();
         auto session = DoCreateTableForPrefixedVectorIndex(db, false);
@@ -3250,6 +3356,8 @@ Y_UNIT_TEST_SUITE(KqpIndexes) {
 
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
 
         auto db = kikimr.GetTableClient();
         auto session = DoCreateTableForPrefixedVectorIndex(db, true);
@@ -3295,6 +3403,8 @@ Y_UNIT_TEST_SUITE(KqpIndexes) {
 
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
 
         auto db = kikimr.GetTableClient();
         auto session = DoCreateTableForPrefixedVectorIndex(db, true);
@@ -3408,6 +3518,8 @@ Y_UNIT_TEST_SUITE(KqpIndexes) {
 
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
         auto db = kikimr.GetTableClient();
         auto session = db.CreateSession().GetValueSync().GetSession();
 
@@ -3485,6 +3597,8 @@ Y_UNIT_TEST_SUITE(KqpIndexes) {
             .SetKqpSettings({setting});
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
         auto db = kikimr.GetTableClient();
         auto session = db.CreateSession().GetValueSync().GetSession();
 
@@ -3636,6 +3750,8 @@ Y_UNIT_TEST_SUITE(KqpIndexes) {
             .SetAppConfig(app);
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
         auto db = kikimr.GetTableClient();
         auto session = db.CreateSession().GetValueSync().GetSession();
 
@@ -3714,6 +3830,8 @@ R"([[#;#;["Primary1"];[41u]];[["Secondary2"];[2u];["Primary2"];[42u]];[["Seconda
             .SetKqpSettings({setting});
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
         auto db = kikimr.GetTableClient();
         auto session = db.CreateSession().GetValueSync().GetSession();
 
@@ -3762,6 +3880,8 @@ R"([[#;#;["Primary1"];[41u]];[["Secondary2"];[2u];["Primary2"];[42u]];[["Seconda
             .SetAppConfig(appConfig);
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
         auto db = kikimr.GetTableClient();
         auto session = db.CreateSession().GetValueSync().GetSession();
 
@@ -3826,6 +3946,8 @@ R"([[#;#;["Primary1"];[41u]];[["Secondary2"];[2u];["Primary2"];[42u]];[["Seconda
             .SetKqpSettings({setting});
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
         auto db = kikimr.GetTableClient();
         auto session = db.CreateSession().GetValueSync().GetSession();
 
@@ -4017,6 +4139,8 @@ R"([[#;#;["Primary1"];[41u]];[["Secondary2"];[2u];["Primary2"];[42u]];[["Seconda
             .SetKqpSettings({setting});
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
         auto db = kikimr.GetTableClient();
         auto session = db.CreateSession().GetValueSync().GetSession();
 
@@ -4144,6 +4268,8 @@ R"([[#;#;["Primary1"];[41u]];[["Secondary2"];[2u];["Primary2"];[42u]];[["Seconda
             .SetAppConfig(app);
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
         auto db = kikimr.GetTableClient();
         auto session = db.CreateSession().GetValueSync().GetSession();
 
@@ -4484,6 +4610,8 @@ R"([[#;#;["Primary1"];[41u]];[["Secondary2"];[2u];["Primary2"];[42u]];[["Seconda
             .SetAppConfig(app);
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
         auto db = kikimr.GetTableClient();
         auto session = db.CreateSession().GetValueSync().GetSession();
 
@@ -4760,6 +4888,8 @@ R"([[#;#;["Primary1"];[41u]];[["Secondary2"];[2u];["Primary2"];[42u]];[["Seconda
             .SetAppConfig(appConfig);
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
         auto db = kikimr.GetTableClient();
         auto session = db.CreateSession().GetValueSync().GetSession();
 
@@ -4998,6 +5128,8 @@ R"([[#;#;["Primary1"];[41u]];[["Secondary2"];[2u];["Primary2"];[42u]];[["Seconda
             .SetAppConfig(appConfig);
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
         auto db = kikimr.GetTableClient();
         auto session = db.CreateSession().GetValueSync().GetSession();
 
@@ -5160,6 +5292,8 @@ R"([[#;#;["Primary1"];[41u]];[["Secondary2"];[2u];["Primary2"];[42u]];[["Seconda
             .SetKqpSettings({setting});
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
         auto db = kikimr.GetTableClient();
         auto session = db.CreateSession().GetValueSync().GetSession();
 
@@ -5247,6 +5381,8 @@ R"([[#;#;["Primary1"];[41u]];[["Secondary2"];[2u];["Primary2"];[42u]];[["Seconda
             .SetKqpSettings({setting});
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
         auto db = kikimr.GetTableClient();
         auto scheme = kikimr.GetSchemeClient();
         auto session = db.CreateSession().GetValueSync().GetSession();
@@ -5297,6 +5433,8 @@ R"([[#;#;["Primary1"];[41u]];[["Secondary2"];[2u];["Primary2"];[42u]];[["Seconda
             .SetKqpSettings({setting});
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
         auto db = kikimr.GetTableClient();
         auto session = db.CreateSession().GetValueSync().GetSession();
 
@@ -5337,6 +5475,8 @@ R"([[#;#;["Primary1"];[41u]];[["Secondary2"];[2u];["Primary2"];[42u]];[["Seconda
             .SetAppConfig(appConfig);
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
         auto db = kikimr.GetTableClient();
         auto session = db.CreateSession().GetValueSync().GetSession();
 
@@ -5424,6 +5564,8 @@ R"([[#;#;["Primary1"];[41u]];[["Secondary2"];[2u];["Primary2"];[42u]];[["Seconda
             .SetKqpSettings({setting});
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
         auto db = kikimr.GetTableClient();
         auto session = db.CreateSession().GetValueSync().GetSession();
 
@@ -5622,6 +5764,8 @@ R"([[#;#;["Primary1"];[41u]];[["Secondary2"];[2u];["Primary2"];[42u]];[["Seconda
         serverSettings.SetAppConfig(appConfig);
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
         auto db = kikimr.GetTableClient();
         auto session = db.CreateSession().GetValueSync().GetSession();
         CreateSampleTablesWithIndex(session);
@@ -5698,6 +5842,8 @@ R"([[#;#;["Primary1"];[41u]];[["Secondary2"];[2u];["Primary2"];[42u]];[["Seconda
             .SetKqpSettings({setting});
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
         auto db = kikimr.GetTableClient();
         auto session = db.CreateSession().GetValueSync().GetSession();
         CreateSampleTablesWithIndex(session);
@@ -5775,6 +5921,8 @@ R"([[#;#;["Primary1"];[41u]];[["Secondary2"];[2u];["Primary2"];[42u]];[["Seconda
             .SetKqpSettings({setting});
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
         auto db = kikimr.GetTableClient();
         auto session = db.CreateSession().GetValueSync().GetSession();
 
@@ -5965,6 +6113,8 @@ R"([[#;#;["Primary1"];[41u]];[["Secondary2"];[2u];["Primary2"];[42u]];[["Seconda
             .SetKqpSettings({setting});
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
 
         TScriptingClient client(kikimr.GetDriver());
         auto scriptResult = client.ExecuteYqlScript(R"(
@@ -6058,6 +6208,8 @@ R"([[#;#;["Primary1"];[41u]];[["Secondary2"];[2u];["Primary2"];[42u]];[["Seconda
             .SetAppConfig(appConfig);
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
 
         auto db = kikimr.GetTableClient();
         auto session = db.CreateSession().GetValueSync().GetSession();
@@ -6115,6 +6267,8 @@ R"([[#;#;["Primary1"];[41u]];[["Secondary2"];[2u];["Primary2"];[42u]];[["Seconda
             .SetKqpSettings({setting});
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
 
         auto db = kikimr.GetTableClient();
         auto session = db.CreateSession().GetValueSync().GetSession();
@@ -6166,6 +6320,8 @@ R"([[#;#;["Primary1"];[41u]];[["Secondary2"];[2u];["Primary2"];[42u]];[["Seconda
             .SetKqpSettings({setting});
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
 
         auto db = kikimr.GetTableClient();
         auto session = db.CreateSession().GetValueSync().GetSession();
@@ -6712,6 +6868,8 @@ R"([[#;#;["Primary1"];[41u]];[["Secondary2"];[2u];["Primary2"];[42u]];[["Seconda
             .SetAppConfig(appConfig);
         TKikimrRunner kikimr(serverSettings);
         kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::BUILD_INDEX, NActors::NLog::PRI_TRACE);
+        kikimr.GetTestServer().GetRuntime()->SetLogPriority(NKikimrServices::FLAT_TX_SCHEMESHARD, NActors::NLog::PRI_TRACE);
+        
         auto db = kikimr.GetTableClient();
         auto session = db.CreateSession().GetValueSync().GetSession();
 
diff --git a/ydb/core/protos/flat_scheme_op.proto b/ydb/core/protos/flat_scheme_op.proto
index 41176fb96b2..fcd3c0adbf2 100644
--- a/ydb/core/protos/flat_scheme_op.proto
+++ b/ydb/core/protos/flat_scheme_op.proto
@@ -1587,6 +1587,7 @@ message TIndexBuildControl {
 
 message TLockConfig {
     optional string Name = 1;
+    optional uint64 LockTxId = 2; // if missing, current tx id is used
 }
 
 message TLockGuard {
diff --git a/ydb/core/tx/schemeshard/schemeshard__operation_apply_build_index.cpp b/ydb/core/tx/schemeshard/schemeshard__operation_apply_build_index.cpp
index 06a5c1fa3e6..ce8f4a7c543 100644
--- a/ydb/core/tx/schemeshard/schemeshard__operation_apply_build_index.cpp
+++ b/ydb/core/tx/schemeshard/schemeshard__operation_apply_build_index.cpp
@@ -30,7 +30,7 @@ ISubOperation::TPtr FinalizeIndexImplTable(TOperationContext& context, const TPa
     return CreateFinalizeBuildIndexImplTable(partId, transaction);
 }
 
-ISubOperation::TPtr DropIndexImplTable(const TPath& index, const TOperationId& nextId, const TOperationId& partId, const TString& name, const TPathId& pathId, bool& rejected) {
+ISubOperation::TPtr DropIndexImplTable(const TPath& index, const TOperationId& nextId, const TOperationId& partId, const TString& name, const TPathId& pathId, const NKikimrSchemeOp::TLockGuard& lockGuard, bool& rejected) {
     TPath implTable = index.Child(name);
     Y_ABORT_UNLESS(implTable->PathId == pathId);
     Y_ABORT_UNLESS(implTable.LeafName() == name);
@@ -48,6 +48,11 @@ ISubOperation::TPtr DropIndexImplTable(const TPath& index, const TOperationId& n
     }
     rejected = false;
     auto transaction = TransactionTemplate(index.PathString(), NKikimrSchemeOp::EOperationType::ESchemeOpDropTable);
+    if (implTable.IsLocked()) {
+        // because some impl tables may be not locked, do not pass lock guard for them
+        // otherwise `CheckLocks` check would fail
+        *transaction.MutableLockGuard() = lockGuard;
+    }
     auto operation = transaction.MutableDrop();
     operation->SetName(name);
     return CreateDropTable(partId, transaction);
@@ -98,7 +103,7 @@ TVector<ISubOperation::TPtr> ApplyBuildIndex(TOperationId nextId, const TTxTrans
             const auto partId = NextPartId(nextId, result);
             if (NTableIndex::IsBuildImplTable(indexImplTableName)) {
                 bool rejected = false;
-                auto op = DropIndexImplTable(index, nextId, partId, indexImplTableName, indexChildItems.second, rejected);
+                auto op = DropIndexImplTable(index, nextId, partId, indexImplTableName, indexChildItems.second, tx.GetLockGuard(), rejected);
                 if (rejected) {
                     return {std::move(op)};
                 }
@@ -153,7 +158,7 @@ TVector<ISubOperation::TPtr> CancelBuildIndex(TOperationId nextId, const TTxTran
         for (auto& indexChildItems : index.Base()->GetChildren()) {
             const auto partId = NextPartId(nextId, result);
             bool rejected = false;
-            auto op = DropIndexImplTable(index, nextId, partId, indexChildItems.first, indexChildItems.second, rejected);
+            auto op = DropIndexImplTable(index, nextId, partId, indexChildItems.first, indexChildItems.second, tx.GetLockGuard(), rejected);
             if (rejected) {
                 return {std::move(op)};
             }
diff --git a/ydb/core/tx/schemeshard/schemeshard__operation_create_lock.cpp b/ydb/core/tx/schemeshard/schemeshard__operation_create_lock.cpp
index e8c02b30c81..07efe6838fa 100644
--- a/ydb/core/tx/schemeshard/schemeshard__operation_create_lock.cpp
+++ b/ydb/core/tx/schemeshard/schemeshard__operation_create_lock.cpp
@@ -95,6 +95,9 @@ public:
     THolder<TProposeResponse> Propose(const TString&, TOperationContext& context) override {
         const auto& workingDir = Transaction.GetWorkingDir();
         const auto& op = Transaction.GetLockConfig();
+        const TTxId lockTxId = op.HasLockTxId()
+            ? TTxId(op.GetLockTxId())
+            : OperationId.GetTxId();
 
         LOG_N("TCreateLock Propose"
             << ": opId# " << OperationId
@@ -158,13 +161,12 @@ public:
         const auto pathId = tablePath.Base()->PathId;
         result->SetPathId(pathId.LocalPathId);
 
-        if (tablePath.LockedBy() == OperationId.GetTxId()) {
+        if (tablePath.LockedBy() == lockTxId) {
             result->SetError(NKikimrScheme::StatusAlreadyExists, TStringBuilder() << "path checks failed"
                 << ", path already locked by this operation"
                 << ", path: " << tablePath.PathString());
             return result;
         }
-
         TString errStr;
         if (!context.SS->CheckLocks(pathId, Transaction, errStr)) {
             result->SetError(NKikimrScheme::StatusMultipleModifications, errStr);
@@ -177,7 +179,7 @@ public:
         context.MemChanges.GrabNewTxState(context.SS, OperationId);
 
         context.DbChanges.PersistPath(pathId);
-        context.DbChanges.PersistLongLock(pathId, OperationId.GetTxId());
+        context.DbChanges.PersistLongLock(pathId, lockTxId);
         context.DbChanges.PersistTxState(OperationId);
 
         Y_ABORT_UNLESS(!context.SS->FindTx(OperationId));
@@ -194,7 +196,7 @@ public:
             context.OnComplete.Dependence(splitOpId.GetTxId(), OperationId.GetTxId());
         }
 
-        context.SS->LockedPaths[pathId] = OperationId.GetTxId();
+        context.SS->LockedPaths[pathId] = lockTxId;
         context.SS->TabletCounters->Simple()[COUNTER_LOCKS_COUNT].Add(1);
 
         context.OnComplete.ActivateTx(OperationId);
diff --git a/ydb/core/tx/schemeshard/schemeshard__operation_drop_lock.cpp b/ydb/core/tx/schemeshard/schemeshard__operation_drop_lock.cpp
index 8fdfeb0a7d0..4e3cc7c7931 100644
--- a/ydb/core/tx/schemeshard/schemeshard__operation_drop_lock.cpp
+++ b/ydb/core/tx/schemeshard/schemeshard__operation_drop_lock.cpp
@@ -164,7 +164,7 @@ public:
         const auto pathId = dstPath.Base()->PathId;
         result->SetPathId(pathId.LocalPathId);
 
-        if (!dstPath.LockedBy()) {
+        if (!dstPath.IsLocked()) {
             result->SetError(TEvSchemeShard::EStatus::StatusAlreadyExists, TStringBuilder() << "path checks failed"
                 << ", path already unlocked"
                 << ", path: " << dstPath.PathString());
diff --git a/ydb/core/tx/schemeshard/schemeshard__table_stats.cpp b/ydb/core/tx/schemeshard/schemeshard__table_stats.cpp
index 9dfaac17560..61f3bb7a082 100644
--- a/ydb/core/tx/schemeshard/schemeshard__table_stats.cpp
+++ b/ydb/core/tx/schemeshard/schemeshard__table_stats.cpp
@@ -484,22 +484,18 @@ bool TTxStoreTableStats::PersistSingleStats(const TPathId& pathId,
         return true;
     }
 
-    {
-        auto path = TPath::Init(pathId, Self);
-        auto checks = path.Check();
-
-        constexpr ui64 deltaShards = 2;
-        checks
-            .PathShardsLimit(deltaShards)
-            .ShardsLimit(deltaShards);
-
-        if (!checks) {
-            LOG_NOTICE_S(ctx, NKikimrServices::FLAT_TX_SCHEMESHARD,
-                         "Do not request full stats from datashard"
-                             << ", datashard: " << datashardId
-                             << ", reason: " << checks.GetError());
-            return true;
-        }
+    auto path = TPath::Init(pathId, Self);
+    auto checks = path.Check();
+    constexpr ui64 deltaShards = 2;
+    checks
+        .PathShardsLimit(deltaShards)
+        .ShardsLimit(deltaShards);
+    if (!checks) {
+        LOG_NOTICE_S(ctx, NKikimrServices::FLAT_TX_SCHEMESHARD,
+                        "Do not request full stats from datashard"
+                            << ", datashard: " << datashardId
+                            << ", reason: " << checks.GetError());
+        return true;
     }
 
     if (newStats.HasBorrowedData) {
@@ -509,6 +505,12 @@ bool TTxStoreTableStats::PersistSingleStats(const TPathId& pathId,
         return true;
     }
 
+    if (path.IsLocked()) {
+        LOG_DEBUG_S(ctx, NKikimrServices::FLAT_TX_SCHEMESHARD,
+            "Postpone split tablet " << datashardId << " because it is locked by " << path.LockedBy());
+        return true;
+    }
+
     // Request histograms from the datashard
     LOG_DEBUG_S(ctx, NKikimrServices::FLAT_TX_SCHEMESHARD,
         "Requesting full tablet stats " << datashardId << " to split it");
diff --git a/ydb/core/tx/schemeshard/schemeshard__table_stats_histogram.cpp b/ydb/core/tx/schemeshard/schemeshard__table_stats_histogram.cpp
index f78ff977165..7ec9bc887f4 100644
--- a/ydb/core/tx/schemeshard/schemeshard__table_stats_histogram.cpp
+++ b/ydb/core/tx/schemeshard/schemeshard__table_stats_histogram.cpp
@@ -341,6 +341,7 @@ bool TTxPartitionHistogram::Execute(TTransactionContext& txc, const TActorContex
     }
 
     TTableInfo::TPtr table = Self->Tables[tableId];
+    auto path = TPath::Init(tableId, Self);
 
     if (!Self->TabletIdToShardIdx.contains(datashardId)) {
         LOG_DEBUG_S(ctx, NKikimrServices::FLAT_TX_SCHEMESHARD,
@@ -355,6 +356,12 @@ bool TTxPartitionHistogram::Execute(TTransactionContext& txc, const TActorContex
         return true;
     }
 
+    if (path.IsLocked()) {
+        LOG_DEBUG_S(ctx, NKikimrServices::FLAT_TX_SCHEMESHARD,
+            "TTxPartitionHistogram Skip locked table tablet " << datashardId << " by " << path.LockedBy());
+        return true;
+    }
+
     auto shardIdx = Self->TabletIdToShardIdx[datashardId];
     const auto forceShardSplitSettings = Self->SplitSettings.GetForceShardSplitSettings();
 
diff --git a/ydb/core/tx/schemeshard/schemeshard_build_index__progress.cpp b/ydb/core/tx/schemeshard/schemeshard_build_index__progress.cpp
index 7e2df90002e..f06974855a0 100644
--- a/ydb/core/tx/schemeshard/schemeshard_build_index__progress.cpp
+++ b/ydb/core/tx/schemeshard/schemeshard_build_index__progress.cpp
@@ -22,45 +22,6 @@
 namespace NKikimr {
 namespace NSchemeShard {
 
-static constexpr const char* Name(TIndexBuildInfo::EState state) noexcept {
-    switch (state) {
-    case TIndexBuildInfo::EState::Invalid:
-        return "Invalid";
-    case TIndexBuildInfo::EState::AlterMainTable:
-        return "AlterMainTable";
-    case TIndexBuildInfo::EState::Locking:
-        return "Locking";
-    case TIndexBuildInfo::EState::GatheringStatistics:
-        return "GatheringStatistics";
-    case TIndexBuildInfo::EState::Initiating:
-        return "Initiating";
-    case TIndexBuildInfo::EState::Filling:
-        return "Filling";
-    case TIndexBuildInfo::EState::DropBuild:
-        return "DropBuild";
-    case TIndexBuildInfo::EState::CreateBuild:
-        return "CreateBuild";
-    case TIndexBuildInfo::EState::Applying:
-        return "Applying";
-    case TIndexBuildInfo::EState::Unlocking:
-        return "Unlocking";
-    case TIndexBuildInfo::EState::Done:
-        return "Done";
-    case TIndexBuildInfo::EState::Cancellation_Applying:
-        return "Cancellation_Applying";
-    case TIndexBuildInfo::EState::Cancellation_Unlocking:
-        return "Cancellation_Unlocking";
-    case TIndexBuildInfo::EState::Cancelled:
-        return "Cancelled";
-    case TIndexBuildInfo::EState::Rejection_Applying:
-        return "Rejection_Applying";
-    case TIndexBuildInfo::EState::Rejection_Unlocking:
-        return "Rejection_Unlocking";
-    case TIndexBuildInfo::EState::Rejected:
-        return "Rejected";
-    }
-}
-
 // return count, parts, step
 static std::tuple<NTableIndex::TClusterId, NTableIndex::TClusterId, NTableIndex::TClusterId> ComputeKMeansBoundaries(const NSchemeShard::TTableInfo& tableInfo, const TIndexBuildInfo& buildInfo) {
     const auto& kmeans = buildInfo.KMeans;
@@ -244,24 +205,32 @@ private:
     }
 };
 
+TPath GetBuildPath(TSchemeShard* ss, const TIndexBuildInfo& buildInfo, const TString& tableName) {
+    return TPath::Init(buildInfo.TablePathId, ss)
+        .Dive(buildInfo.IndexName)
+        .Dive(tableName);
+}
+
 THolder<TEvSchemeShard::TEvModifySchemeTransaction> LockPropose(
-    TSchemeShard* ss, const TIndexBuildInfo& buildInfo)
+    TSchemeShard* ss, const TIndexBuildInfo& buildInfo, TTxId txId, const TPath& path)
 {
-    auto propose = MakeHolder<TEvSchemeShard::TEvModifySchemeTransaction>(ui64(buildInfo.LockTxId), ss->TabletID());
+    auto propose = MakeHolder<TEvSchemeShard::TEvModifySchemeTransaction>(ui64(txId), ss->TabletID());
     propose->Record.SetFailOnExist(false);
 
     NKikimrSchemeOp::TModifyScheme& modifyScheme = *propose->Record.AddTransaction();
     modifyScheme.SetOperationType(NKikimrSchemeOp::ESchemeOpCreateLock);
     modifyScheme.SetInternal(true);
-
-    TPath path = TPath::Init(buildInfo.TablePathId, ss);
     modifyScheme.SetWorkingDir(path.Parent().PathString());
     modifyScheme.MutableLockConfig()->SetName(path.LeafName());
+    modifyScheme.MutableLockConfig()->SetLockTxId(ui64(buildInfo.LockTxId));
+
+    LOG_DEBUG_S((TlsActivationContext->AsActorContext()), NKikimrServices::BUILD_INDEX, 
+        "LockPropose " << buildInfo.Id << " " << buildInfo.State << " " << propose->Record.ShortDebugString());
 
     return propose;
 }
 
-THolder<TEvSchemeShard::TEvModifySchemeTransaction> InitiatePropose(
+THolder<TEvSchemeShard::TEvModifySchemeTransaction> CreateIndexPropose(
     TSchemeShard* ss, const TIndexBuildInfo& buildInfo)
 {
     auto propose = MakeHolder<TEvSchemeShard::TEvModifySchemeTransaction>(ui64(buildInfo.InitiateTxId), ss->TabletID());
@@ -279,9 +248,12 @@ THolder<TEvSchemeShard::TEvModifySchemeTransaction> InitiatePropose(
         modifyScheme.SetOperationType(NKikimrSchemeOp::ESchemeOpCreateColumnBuild);
         buildInfo.SerializeToProto(ss, modifyScheme.MutableInitiateColumnBuild());
     } else {
-        Y_ABORT("Unknown operation kind while building InitiatePropose");
+        Y_ABORT("Unknown operation kind while building CreateIndexPropose");
     }
 
+    LOG_DEBUG_S((TlsActivationContext->AsActorContext()), NKikimrServices::BUILD_INDEX, 
+        "CreateIndexPropose " << buildInfo.Id << " " << buildInfo.State << " " << propose->Record.ShortDebugString());
+
     return propose;
 }
 
@@ -293,14 +265,22 @@ THolder<TEvSchemeShard::TEvModifySchemeTransaction> DropBuildPropose(
     auto propose = MakeHolder<TEvSchemeShard::TEvModifySchemeTransaction>(ui64(buildInfo.ApplyTxId), ss->TabletID());
     propose->Record.SetFailOnExist(true);
 
-    auto path = TPath::Init(buildInfo.TablePathId, ss).Dive(buildInfo.IndexName);
+    auto path = GetBuildPath(ss, buildInfo, buildInfo.KMeans.WriteTo(true));
 
     NKikimrSchemeOp::TModifyScheme& modifyScheme = *propose->Record.AddTransaction();
     modifyScheme.SetInternal(true);
-    modifyScheme.SetWorkingDir(path.PathString());
+    modifyScheme.SetWorkingDir(path.Parent().PathString());
+    if (path.IsLocked()) {
+        // because some impl tables may be not locked, do not pass lock guard for them
+        // otherwise `CheckLocks` check would fail
+        modifyScheme.MutableLockGuard()->SetOwnerTxId(ui64(buildInfo.LockTxId));
+    }
 
     modifyScheme.SetOperationType(NKikimrSchemeOp::ESchemeOpDropTable);
-    modifyScheme.MutableDrop()->SetName(buildInfo.KMeans.WriteTo(true));
+    modifyScheme.MutableDrop()->SetName(path->Name);
+
+    LOG_DEBUG_S((TlsActivationContext->AsActorContext()), NKikimrServices::BUILD_INDEX, 
+        "DropBuildPropose " << buildInfo.Id << " " << buildInfo.State << " " << propose->Record.ShortDebugString());
 
     return propose;
 }
@@ -333,10 +313,6 @@ THolder<TEvSchemeShard::TEvModifySchemeTransaction> CreateBuildPropose(
         modifyScheme.ClearInitiateIndexBuild();
     }
 
-    // TODO(mbkkt) for levels greater than zero we need to disable split/merge completely
-    // For now it's not guranteed, but very likely
-    // But lock is really unconvinient approach (needs to store TxId/etc)
-    // So maybe best way to do this is specify something in defintion, that will prevent these operations like IsBackup
     using namespace NTableIndex::NTableVectorKmeansTreeIndex;
     modifyScheme.SetWorkingDir(path.Dive(buildInfo.IndexName).PathString());
     modifyScheme.SetOperationType(NKikimrSchemeOp::ESchemeOpInitiateBuildIndexImplTable);
@@ -361,6 +337,10 @@ THolder<TEvSchemeShard::TEvModifySchemeTransaction> CreateBuildPropose(
         const auto shards = tableInfo->GetShard2PartitionIdx().size();
         policy.SetMinPartitionsCount(shards);
         policy.SetMaxPartitionsCount(shards);
+
+        LOG_DEBUG_S((TlsActivationContext->AsActorContext()), NKikimrServices::BUILD_INDEX, 
+            "CreateBuildPropose " << buildInfo.Id << " " << buildInfo.State << " " << propose->Record.ShortDebugString());
+
         return propose;
     }
     op = CalcVectorKmeansTreePostingImplTableDesc({}, tableInfo, tableInfo->PartitionConfig(), implTableColumns, {}, suffix);
@@ -381,6 +361,10 @@ THolder<TEvSchemeShard::TEvModifySchemeTransaction> CreateBuildPropose(
     }
     policy.SetMinPartitionsCount(op.SplitBoundarySize() + 1);
     policy.SetMaxPartitionsCount(op.SplitBoundarySize() + 1);
+
+    LOG_DEBUG_S((TlsActivationContext->AsActorContext()), NKikimrServices::BUILD_INDEX, 
+        "CreateBuildPropose " << buildInfo.Id << " " << buildInfo.State << " " << propose->Record.ShortDebugString());
+
     return propose;
 }
 
@@ -426,6 +410,9 @@ THolder<TEvSchemeShard::TEvModifySchemeTransaction> AlterMainTablePropose(
 
     }
 
+    LOG_DEBUG_S((TlsActivationContext->AsActorContext()), NKikimrServices::BUILD_INDEX, 
+        "AlterMainTablePropose " << buildInfo.Id << " " << buildInfo.State << " " << propose->Record.ShortDebugString());
+
     return propose;
 }
 
@@ -438,9 +425,7 @@ THolder<TEvSchemeShard::TEvModifySchemeTransaction> ApplyPropose(
     NKikimrSchemeOp::TModifyScheme& modifyScheme = *propose->Record.AddTransaction();
     modifyScheme.SetOperationType(NKikimrSchemeOp::ESchemeOpApplyIndexBuild);
     modifyScheme.SetInternal(true);
-
     modifyScheme.SetWorkingDir(TPath::Init(buildInfo.DomainPathId, ss).PathString());
-
     modifyScheme.MutableLockGuard()->SetOwnerTxId(ui64(buildInfo.LockTxId));
 
     auto& indexBuild = *modifyScheme.MutableApplyIndexBuild();
@@ -453,6 +438,9 @@ THolder<TEvSchemeShard::TEvModifySchemeTransaction> ApplyPropose(
     indexBuild.SetSnapshotTxId(ui64(buildInfo.InitiateTxId));
     indexBuild.SetBuildIndexId(ui64(buildInfo.Id));
 
+    LOG_DEBUG_S((TlsActivationContext->AsActorContext()), NKikimrServices::BUILD_INDEX, 
+        "ApplyPropose " << buildInfo.Id << " " << buildInfo.State << " " << propose->Record.ShortDebugString());
+
     return propose;
 }
 
@@ -465,7 +453,6 @@ THolder<TEvSchemeShard::TEvModifySchemeTransaction> UnlockPropose(
     NKikimrSchemeOp::TModifyScheme& modifyScheme = *propose->Record.AddTransaction();
     modifyScheme.SetOperationType(NKikimrSchemeOp::ESchemeOpDropLock);
     modifyScheme.SetInternal(true);
-
     modifyScheme.MutableLockGuard()->SetOwnerTxId(ui64(buildInfo.LockTxId));
 
     TPath path = TPath::Init(buildInfo.TablePathId, ss);
@@ -474,6 +461,9 @@ THolder<TEvSchemeShard::TEvModifySchemeTransaction> UnlockPropose(
     auto& lockConfig = *modifyScheme.MutableLockConfig();
     lockConfig.SetName(path.LeafName());
 
+    LOG_DEBUG_S((TlsActivationContext->AsActorContext()), NKikimrServices::BUILD_INDEX, 
+        "UnlockPropose " << buildInfo.Id << " " << buildInfo.State << " " << propose->Record.ShortDebugString());
+
     return propose;
 }
 
@@ -486,9 +476,7 @@ THolder<TEvSchemeShard::TEvModifySchemeTransaction> CancelPropose(
     NKikimrSchemeOp::TModifyScheme& modifyScheme = *propose->Record.AddTransaction();
     modifyScheme.SetOperationType(NKikimrSchemeOp::ESchemeOpCancelIndexBuild);
     modifyScheme.SetInternal(true);
-
     modifyScheme.SetWorkingDir(TPath::Init(buildInfo.DomainPathId, ss).PathString());
-
     modifyScheme.MutableLockGuard()->SetOwnerTxId(ui64(buildInfo.LockTxId));
 
     auto& indexBuild = *modifyScheme.MutableCancelIndexBuild();
@@ -497,6 +485,9 @@ THolder<TEvSchemeShard::TEvModifySchemeTransaction> CancelPropose(
     indexBuild.SetSnapshotTxId(ui64(buildInfo.InitiateTxId));
     indexBuild.SetBuildIndexId(ui64(buildInfo.Id));
 
+    LOG_DEBUG_S((TlsActivationContext->AsActorContext()), NKikimrServices::BUILD_INDEX, 
+        "CancelPropose " << buildInfo.Id << " " << buildInfo.State << " " << propose->Record.ShortDebugString());
+
     return propose;
 }
 
@@ -543,8 +534,8 @@ private:
         if (buildInfo.KMeans.Level == 1) {
             buildInfo.TablePathId.ToProto(ev->Record.MutablePathId());
         } else {
-            auto path = TPath::Init(buildInfo.TablePathId, Self).Dive(buildInfo.IndexName);
-            path.Dive(buildInfo.KMeans.ReadFrom())->PathId.ToProto(ev->Record.MutablePathId());
+            auto path = GetBuildPath(Self, buildInfo, buildInfo.KMeans.ReadFrom());
+            path->PathId.ToProto(ev->Record.MutablePathId());
         }
 
         ev->Record.SetK(buildInfo.KMeans.K);
@@ -666,8 +657,8 @@ private:
         auto ev = MakeHolder<TEvDataShard::TEvPrefixKMeansRequest>();
         ev->Record.SetId(ui64(BuildId));
 
-        auto path = TPath::Init(buildInfo.TablePathId, Self).Dive(buildInfo.IndexName);
-        path.Dive(buildInfo.KMeans.ReadFrom())->PathId.ToProto(ev->Record.MutablePathId());
+        auto path = GetBuildPath(Self, buildInfo, buildInfo.KMeans.ReadFrom());
+        path->PathId.ToProto(ev->Record.MutablePathId());
         path.Rise();
         *ev->Record.MutableSettings() = std::get<NKikimrSchemeOp::TVectorIndexKmeansTreeDescription>(
             buildInfo.SpecializedIndexDescription).GetSettings().settings();
@@ -710,7 +701,7 @@ private:
             buildInfo.SerializeToProto(Self, ev->Record.MutableColumnBuildSettings());
         } else {
             if (buildInfo.TargetName.empty()) {
-                TPath implTable = TPath::Init(buildInfo.TablePathId, Self).Dive(buildInfo.IndexName).Dive(
+                TPath implTable = GetBuildPath(Self, buildInfo,
                     buildInfo.IsBuildPrefixedVectorIndex() ? buildInfo.KMeans.WriteTo() : NTableIndex::ImplTable);
                 buildInfo.TargetName = implTable.PathString();
 
@@ -752,9 +743,7 @@ private:
 
     void SendUploadSampleKRequest(TIndexBuildInfo& buildInfo) {
         buildInfo.Sample.MakeStrictTop(buildInfo.KMeans.K);
-        auto path = TPath::Init(buildInfo.TablePathId, Self)
-                        .Dive(buildInfo.IndexName)
-                        .Dive(NTableIndex::NTableVectorKmeansTreeIndex::LevelTable);
+        auto path = GetBuildPath(Self, buildInfo, NTableIndex::NTableVectorKmeansTreeIndex::LevelTable);
         Y_ASSERT(buildInfo.Sample.Rows.size() <= buildInfo.KMeans.K);
         auto actor = new TUploadSampleK(path.PathString(),
             buildInfo.ScanSettings, Self->SelfId(), ui64(BuildId),
@@ -1084,7 +1073,9 @@ private:
         }
         if (buildInfo.Shards.empty()) {
             NIceDb::TNiceDb db(txc.DB);
-            InitiateShards(db, buildInfo);
+            if (!InitiateShards(db, buildInfo)) {
+                return false;
+            }
         }
         switch (buildInfo.BuildKind) {
             case TIndexBuildInfo::EBuildKind::BuildSecondaryIndex:
@@ -1111,8 +1102,7 @@ public:
         Y_ABORT_UNLESS(buildInfoPtr);
         auto& buildInfo = *buildInfoPtr->Get();
 
-        LOG_I("TTxBuildProgress: Resume: id# " << BuildId);
-        LOG_D("TTxBuildProgress: Resume: " << buildInfo);
+        LOG_I("TTxBuildProgress: Execute: " << BuildId << " " << buildInfo.State << " " << buildInfo);
 
         switch (buildInfo.State) {
         case TIndexBuildInfo::EState::Invalid:
@@ -1120,7 +1110,7 @@ public:
 
         case TIndexBuildInfo::EState::AlterMainTable:
             if (buildInfo.AlterMainTableTxId == InvalidTxId) {
-                Send(Self->TxAllocatorClient, MakeHolder<TEvTxAllocatorClient::TEvAllocate>(), 0, ui64(BuildId));
+                AllocateTxId(BuildId);
             } else if (buildInfo.AlterMainTableTxStatus == NKikimrScheme::StatusSuccess) {
                 Send(Self->SelfId(), AlterMainTablePropose(Self, buildInfo), 0, ui64(BuildId));
             } else if (!buildInfo.AlterMainTableTxDone) {
@@ -1132,9 +1122,9 @@ public:
             break;
         case TIndexBuildInfo::EState::Locking:
             if (buildInfo.LockTxId == InvalidTxId) {
-                Send(Self->TxAllocatorClient, MakeHolder<TEvTxAllocatorClient::TEvAllocate>(), 0, ui64(BuildId));
+                AllocateTxId(BuildId);
             } else if (buildInfo.LockTxStatus == NKikimrScheme::StatusSuccess) {
-                Send(Self->SelfId(), LockPropose(Self, buildInfo), 0, ui64(BuildId));
+                Send(Self->SelfId(), LockPropose(Self, buildInfo, buildInfo.LockTxId, TPath::Init(buildInfo.TablePathId, Self)), 0, ui64(BuildId));
             } else if (!buildInfo.LockTxDone) {
                 Send(Self->SelfId(), MakeHolder<TEvSchemeShard::TEvNotifyTxCompletion>(ui64(buildInfo.LockTxId)));
             } else {
@@ -1149,9 +1139,9 @@ public:
             break;
         case TIndexBuildInfo::EState::Initiating:
             if (buildInfo.InitiateTxId == InvalidTxId) {
-                Send(Self->TxAllocatorClient, MakeHolder<TEvTxAllocatorClient::TEvAllocate>(), 0, ui64(BuildId));
+                AllocateTxId(BuildId);
             } else if (buildInfo.InitiateTxStatus == NKikimrScheme::StatusSuccess) {
-                Send(Self->SelfId(), InitiatePropose(Self, buildInfo), 0, ui64(BuildId));
+                Send(Self->SelfId(), CreateIndexPropose(Self, buildInfo), 0, ui64(BuildId));
             } else if (!buildInfo.InitiateTxDone) {
                 Send(Self->SelfId(), MakeHolder<TEvSchemeShard::TEvNotifyTxCompletion>(ui64(buildInfo.InitiateTxId)));
             } else {
@@ -1184,7 +1174,7 @@ public:
             Y_ASSERT(buildInfo.IsBuildVectorIndex());
             Y_ASSERT(buildInfo.KMeans.Level > 2);
             if (buildInfo.ApplyTxId == InvalidTxId) {
-                Send(Self->TxAllocatorClient, MakeHolder<TEvTxAllocatorClient::TEvAllocate>(), 0, ui64(BuildId));
+                AllocateTxId(BuildId);
             } else if (buildInfo.ApplyTxStatus == NKikimrScheme::StatusSuccess) {
                 Send(Self->SelfId(), DropBuildPropose(Self, buildInfo), 0, ui64(BuildId));
             } else if (!buildInfo.ApplyTxDone) {
@@ -1206,7 +1196,7 @@ public:
         case TIndexBuildInfo::EState::CreateBuild:
             Y_ASSERT(buildInfo.IsBuildVectorIndex());
             if (buildInfo.ApplyTxId == InvalidTxId) {
-                Send(Self->TxAllocatorClient, MakeHolder<TEvTxAllocatorClient::TEvAllocate>(), 0, ui64(BuildId));
+                AllocateTxId(BuildId);
             } else if (buildInfo.ApplyTxStatus == NKikimrScheme::StatusSuccess) {
                 Send(Self->SelfId(), CreateBuildPropose(Self, buildInfo), 0, ui64(BuildId));
             } else if (!buildInfo.ApplyTxDone) {
@@ -1228,9 +1218,31 @@ public:
                 Progress(BuildId);
             }
             break;
+        case TIndexBuildInfo::EState::LockBuild:
+            Y_ASSERT(buildInfo.IsBuildVectorIndex());
+            if (buildInfo.ApplyTxId == InvalidTxId) {
+                AllocateTxId(BuildId);
+            } else if (buildInfo.ApplyTxStatus == NKikimrScheme::StatusSuccess) {
+                Send(Self->SelfId(), LockPropose(Self, buildInfo, buildInfo.ApplyTxId, GetBuildPath(Self, buildInfo, buildInfo.KMeans.ReadFrom())), 0, ui64(BuildId));
+            } else if (!buildInfo.ApplyTxDone) {
+                Send(Self->SelfId(), MakeHolder<TEvSchemeShard::TEvNotifyTxCompletion>(ui64(buildInfo.ApplyTxId)));
+            } else {
+                buildInfo.ApplyTxId = {};
+                buildInfo.ApplyTxStatus = NKikimrScheme::StatusSuccess;
+                buildInfo.ApplyTxDone = false;
+
+                NIceDb::TNiceDb db(txc.DB);
+                Self->PersistBuildIndexApplyTxId(db, buildInfo);
+                Self->PersistBuildIndexApplyTxStatus(db, buildInfo);
+                Self->PersistBuildIndexApplyTxDone(db, buildInfo);
+
+                ChangeState(BuildId, TIndexBuildInfo::EState::Filling);
+                Progress(BuildId);
+            }
+            break;
         case TIndexBuildInfo::EState::Applying:
             if (buildInfo.ApplyTxId == InvalidTxId) {
-                Send(Self->TxAllocatorClient, MakeHolder<TEvTxAllocatorClient::TEvAllocate>(), 0, ui64(BuildId));
+                AllocateTxId(BuildId);
             } else if (buildInfo.ApplyTxStatus == NKikimrScheme::StatusSuccess) {
                 Send(Self->SelfId(), ApplyPropose(Self, buildInfo), 0, ui64(BuildId));
             } else if (!buildInfo.ApplyTxDone) {
@@ -1242,7 +1254,7 @@ public:
             break;
         case TIndexBuildInfo::EState::Unlocking:
             if (buildInfo.UnlockTxId == InvalidTxId) {
-                Send(Self->TxAllocatorClient, MakeHolder<TEvTxAllocatorClient::TEvAllocate>(), 0, ui64(BuildId));
+                AllocateTxId(BuildId);
             } else if (buildInfo.UnlockTxStatus == NKikimrScheme::StatusSuccess) {
                 Send(Self->SelfId(), UnlockPropose(Self, buildInfo), 0, ui64(BuildId));
             } else if (!buildInfo.UnlockTxDone) {
@@ -1258,7 +1270,7 @@ public:
             break;
         case TIndexBuildInfo::EState::Cancellation_Applying:
             if (buildInfo.ApplyTxId == InvalidTxId) {
-                Send(Self->TxAllocatorClient, MakeHolder<TEvTxAllocatorClient::TEvAllocate>(), 0, ui64(BuildId));
+                AllocateTxId(BuildId);
             } else if (buildInfo.ApplyTxStatus == NKikimrScheme::StatusSuccess) {
                 Send(Self->SelfId(), CancelPropose(Self, buildInfo), 0, ui64(BuildId));
             } else if (!buildInfo.ApplyTxDone) {
@@ -1270,7 +1282,7 @@ public:
             break;
         case TIndexBuildInfo::EState::Cancellation_Unlocking:
             if (buildInfo.UnlockTxId == InvalidTxId) {
-                Send(Self->TxAllocatorClient, MakeHolder<TEvTxAllocatorClient::TEvAllocate>(), 0, ui64(BuildId));
+                AllocateTxId(BuildId);
             } else if (buildInfo.UnlockTxStatus == NKikimrScheme::StatusSuccess) {
                 Send(Self->SelfId(), UnlockPropose(Self, buildInfo), 0, ui64(BuildId));
             } else if (!buildInfo.UnlockTxDone) {
@@ -1286,7 +1298,7 @@ public:
             break;
         case TIndexBuildInfo::EState::Rejection_Applying:
             if (buildInfo.ApplyTxId == InvalidTxId) {
-                Send(Self->TxAllocatorClient, MakeHolder<TEvTxAllocatorClient::TEvAllocate>(), 0, ui64(BuildId));
+                AllocateTxId(BuildId);
             } else if (buildInfo.ApplyTxStatus == NKikimrScheme::StatusSuccess) {
                 Send(Self->SelfId(), CancelPropose(Self, buildInfo), 0, ui64(BuildId));
             } else if (!buildInfo.ApplyTxDone) {
@@ -1298,7 +1310,7 @@ public:
             break;
         case TIndexBuildInfo::EState::Rejection_Unlocking:
             if (buildInfo.UnlockTxId == InvalidTxId) {
-                Send(Self->TxAllocatorClient, MakeHolder<TEvTxAllocatorClient::TEvAllocate>(), 0, ui64(BuildId));
+                AllocateTxId(BuildId);
             } else if (buildInfo.UnlockTxStatus == NKikimrScheme::StatusSuccess) {
                 Send(Self->SelfId(), UnlockPropose(Self, buildInfo), 0, ui64(BuildId));
             } else if (!buildInfo.UnlockTxDone) {
@@ -1332,7 +1344,7 @@ public:
         return TSerializedTableRange{{&from, 1}, false, {&to, 1}, true};
     }
 
-    void InitiateShards(NIceDb::TNiceDb& db, TIndexBuildInfo& buildInfo) {
+    bool InitiateShards(NIceDb::TNiceDb& db, TIndexBuildInfo& buildInfo) {
         LOG_D("InitiateShards " << buildInfo.DebugString());
 
         Y_ASSERT(buildInfo.Shards.empty());
@@ -1344,8 +1356,15 @@ public:
         if (buildInfo.KMeans.Level == 1) {
             table = Self->Tables.at(buildInfo.TablePathId);
         } else {
-            auto path = TPath::Init(buildInfo.TablePathId, Self).Dive(buildInfo.IndexName);
-            table = Self->Tables.at(path.Dive(buildInfo.KMeans.ReadFrom())->PathId);
+            auto path = GetBuildPath(Self, buildInfo, buildInfo.KMeans.ReadFrom());
+            table = Self->Tables.at(path->PathId);
+
+            if (!path.IsLocked()) { // lock is needed to prevent table shards from being split
+                ChangeState(buildInfo.Id, TIndexBuildInfo::EState::LockBuild);
+                Progress(buildInfo.Id);
+                return false;
+            }
+            Y_ASSERT(path.LockedBy() == buildInfo.LockTxId);
         }
         auto tableColumns = NTableIndex::ExtractInfo(table); // skip dropped columns
         TSerializedTableRange shardRange = InfiniteRange(tableColumns.Keys.size());
@@ -1366,6 +1385,8 @@ public:
 
             Self->PersistBuildIndexUploadInitiate(db, BuildId, x.ShardIdx, it->second);
         }
+
+        return true;
     }
 
     void DoComplete(const TActorContext& ctx) override {
@@ -1483,10 +1504,11 @@ public:
         case TIndexBuildInfo::EState::Initiating:
         case TIndexBuildInfo::EState::DropBuild:
         case TIndexBuildInfo::EState::CreateBuild:
+        case TIndexBuildInfo::EState::LockBuild:
         case TIndexBuildInfo::EState::Applying:
         case TIndexBuildInfo::EState::Unlocking:
         case TIndexBuildInfo::EState::Done:
-            Y_FAIL_S("Unreachable " << Name(state));
+            Y_FAIL_S("Unreachable " << state);
         case TIndexBuildInfo::EState::Cancellation_Applying:
         case TIndexBuildInfo::EState::Cancellation_Unlocking:
         case TIndexBuildInfo::EState::Cancelled:
@@ -1637,10 +1659,11 @@ public:
         case TIndexBuildInfo::EState::Initiating:
         case TIndexBuildInfo::EState::DropBuild:
         case TIndexBuildInfo::EState::CreateBuild:
+        case TIndexBuildInfo::EState::LockBuild:
         case TIndexBuildInfo::EState::Applying:
         case TIndexBuildInfo::EState::Unlocking:
         case TIndexBuildInfo::EState::Done:
-            Y_FAIL_S("Unreachable " << Name(state));
+            Y_FAIL_S("Unreachable " << state);
         case TIndexBuildInfo::EState::Cancellation_Applying:
         case TIndexBuildInfo::EState::Cancellation_Unlocking:
         case TIndexBuildInfo::EState::Cancelled:
@@ -1762,10 +1785,11 @@ public:
         case TIndexBuildInfo::EState::Initiating:
         case TIndexBuildInfo::EState::DropBuild:
         case TIndexBuildInfo::EState::CreateBuild:
+        case TIndexBuildInfo::EState::LockBuild:
         case TIndexBuildInfo::EState::Applying:
         case TIndexBuildInfo::EState::Unlocking:
         case TIndexBuildInfo::EState::Done:
-            Y_FAIL_S("Unreachable " << Name(state));
+            Y_FAIL_S("Unreachable " << state);
         case TIndexBuildInfo::EState::Cancellation_Applying:
         case TIndexBuildInfo::EState::Cancellation_Unlocking:
         case TIndexBuildInfo::EState::Cancelled:
@@ -1886,10 +1910,11 @@ public:
         case TIndexBuildInfo::EState::Initiating:
         case TIndexBuildInfo::EState::DropBuild:
         case TIndexBuildInfo::EState::CreateBuild:
+        case TIndexBuildInfo::EState::LockBuild:
         case TIndexBuildInfo::EState::Applying:
         case TIndexBuildInfo::EState::Unlocking:
         case TIndexBuildInfo::EState::Done:
-            Y_FAIL_S("Unreachable " << Name(state));
+            Y_FAIL_S("Unreachable " << state);
         case TIndexBuildInfo::EState::Cancellation_Applying:
         case TIndexBuildInfo::EState::Cancellation_Unlocking:
         case TIndexBuildInfo::EState::Cancelled:
@@ -2011,10 +2036,11 @@ public:
         case TIndexBuildInfo::EState::Initiating:
         case TIndexBuildInfo::EState::DropBuild:
         case TIndexBuildInfo::EState::CreateBuild:
+        case TIndexBuildInfo::EState::LockBuild:
         case TIndexBuildInfo::EState::Applying:
         case TIndexBuildInfo::EState::Unlocking:
         case TIndexBuildInfo::EState::Done:
-            Y_FAIL_S("Unreachable " << Name(state));
+            Y_FAIL_S("Unreachable " << state);
         case TIndexBuildInfo::EState::Cancellation_Applying:
         case TIndexBuildInfo::EState::Cancellation_Unlocking:
         case TIndexBuildInfo::EState::Cancelled:
@@ -2093,10 +2119,11 @@ public:
         case TIndexBuildInfo::EState::Initiating:
         case TIndexBuildInfo::EState::DropBuild:
         case TIndexBuildInfo::EState::CreateBuild:
+        case TIndexBuildInfo::EState::LockBuild:
         case TIndexBuildInfo::EState::Applying:
         case TIndexBuildInfo::EState::Unlocking:
         case TIndexBuildInfo::EState::Done:
-            Y_FAIL_S("Unreachable " << Name(state));
+            Y_FAIL_S("Unreachable " << state);
         case TIndexBuildInfo::EState::Cancellation_Applying:
         case TIndexBuildInfo::EState::Cancellation_Unlocking:
         case TIndexBuildInfo::EState::Cancelled:
@@ -2246,10 +2273,11 @@ public:
         case TIndexBuildInfo::EState::Initiating:
         case TIndexBuildInfo::EState::DropBuild:
         case TIndexBuildInfo::EState::CreateBuild:
+        case TIndexBuildInfo::EState::LockBuild:
         case TIndexBuildInfo::EState::Applying:
         case TIndexBuildInfo::EState::Unlocking:
         case TIndexBuildInfo::EState::Done:
-            Y_FAIL_S("Unreachable " << Name(state));
+            Y_FAIL_S("Unreachable " << state);
         case TIndexBuildInfo::EState::Cancellation_Applying:
         case TIndexBuildInfo::EState::Cancellation_Unlocking:
         case TIndexBuildInfo::EState::Cancelled:
@@ -2325,6 +2353,7 @@ public:
         }
         case TIndexBuildInfo::EState::DropBuild:
         case TIndexBuildInfo::EState::CreateBuild:
+        case TIndexBuildInfo::EState::LockBuild:
         case TIndexBuildInfo::EState::Applying:
         case TIndexBuildInfo::EState::Cancellation_Applying:
         case TIndexBuildInfo::EState::Rejection_Applying:
@@ -2351,7 +2380,7 @@ public:
         case TIndexBuildInfo::EState::Done:
         case TIndexBuildInfo::EState::Cancelled:
         case TIndexBuildInfo::EState::Rejected:
-            Y_FAIL_S("Unreachable " << Name(state));
+            Y_FAIL_S("Unreachable " << state);
         }
 
         Progress(buildId);
@@ -2432,7 +2461,7 @@ public:
 
             if (statusCode != Ydb::StatusIds::SUCCESS) {
                 buildInfo.Issue += TStringBuilder()
-                    << "At " << Name(state) << " state got unsuccess propose result"
+                    << "At " << state << " state got unsuccess propose result"
                     << ", status: " << NKikimrScheme::EStatus_Name(record.GetStatus())
                     << ", reason: " << record.GetReason();
                 Self->PersistBuildIndexIssue(db, buildInfo);
@@ -2451,7 +2480,7 @@ public:
                 // no op
             } else {
                 buildInfo.Issue += TStringBuilder()
-                    << "At " << Name(state) << " state got unsuccess propose result"
+                    << "At " << state << " state got unsuccess propose result"
                     << ", status: " << NKikimrScheme::EStatus_Name(record.GetStatus())
                     << ", reason: " << record.GetReason();
                 Self->PersistBuildIndexIssue(db, buildInfo);
@@ -2492,6 +2521,7 @@ public:
         }
         case TIndexBuildInfo::EState::DropBuild:
         case TIndexBuildInfo::EState::CreateBuild:
+        case TIndexBuildInfo::EState::LockBuild:
         case TIndexBuildInfo::EState::Applying:
         case TIndexBuildInfo::EState::Rejection_Applying:
         {
@@ -2549,7 +2579,7 @@ public:
         case TIndexBuildInfo::EState::Done:
         case TIndexBuildInfo::EState::Cancelled:
         case TIndexBuildInfo::EState::Rejected:
-            Y_FAIL_S("Unreachable " << Name(state));
+            Y_FAIL_S("Unreachable " << state);
         }
 
         Progress(buildId);
@@ -2606,6 +2636,7 @@ public:
             break;
         case TIndexBuildInfo::EState::DropBuild:
         case TIndexBuildInfo::EState::CreateBuild:
+        case TIndexBuildInfo::EState::LockBuild:
         case TIndexBuildInfo::EState::Applying:
         case TIndexBuildInfo::EState::Cancellation_Applying:
         case TIndexBuildInfo::EState::Rejection_Applying:
@@ -2628,7 +2659,7 @@ public:
         case TIndexBuildInfo::EState::Done:
         case TIndexBuildInfo::EState::Cancelled:
         case TIndexBuildInfo::EState::Rejected:
-            Y_FAIL_S("Unreachable " << Name(state));
+            Y_FAIL_S("Unreachable " << state);
         }
 
         Progress(buildId);
diff --git a/ydb/core/tx/schemeshard/schemeshard_build_index_tx_base.cpp b/ydb/core/tx/schemeshard/schemeshard_build_index_tx_base.cpp
index e07d231c38e..9a3eecc5076 100644
--- a/ydb/core/tx/schemeshard/schemeshard_build_index_tx_base.cpp
+++ b/ydb/core/tx/schemeshard/schemeshard_build_index_tx_base.cpp
@@ -177,6 +177,11 @@ void TSchemeShard::TIndexBuilder::TTxBase::Send(TActorId dst, THolder<IEventBase
     SideEffects.Send(dst, message.Release(), cookie, flags);
 }
 
+void TSchemeShard::TIndexBuilder::TTxBase::AllocateTxId(TIndexBuildId buildId) {
+    LOG_D("AllocateTxId " << buildId);
+    Send(Self->TxAllocatorClient, MakeHolder<TEvTxAllocatorClient::TEvAllocate>(), 0, ui64(buildId));
+}
+
 void TSchemeShard::TIndexBuilder::TTxBase::ChangeState(TIndexBuildId id, TIndexBuildInfo::EState state) {
     StateChanges.push_back(TChangeStateRec(id, state));
 }
@@ -215,6 +220,7 @@ void TSchemeShard::TIndexBuilder::TTxBase::Fill(NKikimrIndexBuilder::TIndexBuild
     case TIndexBuildInfo::EState::Filling:
     case TIndexBuildInfo::EState::DropBuild:
     case TIndexBuildInfo::EState::CreateBuild:
+    case TIndexBuildInfo::EState::LockBuild:
         index.SetState(Ydb::Table::IndexBuildState::STATE_TRANSFERING_DATA);
         index.SetProgress(indexInfo.CalcProgressPercent());
         break;
diff --git a/ydb/core/tx/schemeshard/schemeshard_build_index_tx_base.h b/ydb/core/tx/schemeshard/schemeshard_build_index_tx_base.h
index 1a70dd31ec5..02f96b34aef 100644
--- a/ydb/core/tx/schemeshard/schemeshard_build_index_tx_base.h
+++ b/ydb/core/tx/schemeshard/schemeshard_build_index_tx_base.h
@@ -32,6 +32,7 @@ private:
 
 protected:
     void Send(TActorId dst, THolder<IEventBase> message, ui32 flags = 0, ui64 cookie = 0);
+    void AllocateTxId(TIndexBuildId buildId);
     void ChangeState(TIndexBuildId id, TIndexBuildInfo::EState state);
     void Progress(TIndexBuildId id);
     void Fill(NKikimrIndexBuilder::TIndexBuild& index, const TIndexBuildInfo& indexInfo);
diff --git a/ydb/core/tx/schemeshard/schemeshard_info_types.h b/ydb/core/tx/schemeshard/schemeshard_info_types.h
index 50f489a1e90..d6b90d7e3bc 100644
--- a/ydb/core/tx/schemeshard/schemeshard_info_types.h
+++ b/ydb/core/tx/schemeshard/schemeshard_info_types.h
@@ -3040,6 +3040,7 @@ struct TIndexBuildInfo: public TSimpleRefCount<TIndexBuildInfo> {
         Filling = 40,
         DropBuild = 45,
         CreateBuild = 46,
+        LockBuild = 47,
         Applying = 50,
         Unlocking = 60,
         Done = 200,
diff --git a/ydb/core/tx/schemeshard/schemeshard_path.cpp b/ydb/core/tx/schemeshard/schemeshard_path.cpp
index 01bae14754e..c62f7be2d41 100644
--- a/ydb/core/tx/schemeshard/schemeshard_path.cpp
+++ b/ydb/core/tx/schemeshard/schemeshard_path.cpp
@@ -1875,6 +1875,10 @@ ui64 TPath::GetEffectiveACLVersion() const {
     return version;
 }
 
+bool TPath::IsLocked() const {
+    return SS->LockedPaths.contains(Base()->PathId);
+}
+
 TTxId TPath::LockedBy() const {
     auto it = SS->LockedPaths.find(Base()->PathId);
     if (it != SS->LockedPaths.end()) {
diff --git a/ydb/core/tx/schemeshard/schemeshard_path.h b/ydb/core/tx/schemeshard/schemeshard_path.h
index 4e167ac23dc..071e488b7b8 100644
--- a/ydb/core/tx/schemeshard/schemeshard_path.h
+++ b/ydb/core/tx/schemeshard/schemeshard_path.h
@@ -183,6 +183,7 @@ public:
     bool IsValidLeafName(TString& explain) const;
     TString GetEffectiveACL() const;
     ui64 GetEffectiveACLVersion() const;
+    bool IsLocked() const;
     TTxId LockedBy() const;
 
     bool IsActive() const;