ddl: Fix adding vector index on empty table may blocked forever

dbms/src/Interpreters/InterpreterSelectQuery.cpp

@@ -243,7 +243,6 @@ void InterpreterSelectQuery::getAndLockStorageWithSchemaVersion(const String & d
             || (managed_storage->engineType() != ::TiDB::StorageEngine::DT
                 && managed_storage->engineType() != ::TiDB::StorageEngine::TMT))
         {
-            LOG_DEBUG(log, "{}.{} is not ManageableStorage", database_name, table_name);
             storage = storage_tmp;
             table_lock = storage->lockForShare(context.getCurrentQueryId());
             return;

dbms/src/Storages/DeltaMerge/DeltaMergeStore.h

@@ -575,7 +575,10 @@ class DeltaMergeStore
 
     StoreStats getStoreStats();
     SegmentsStats getSegmentsStats();
+
     LocalIndexesStats getLocalIndexStats();
+    // Generate local index stats for non inited DeltaMergeStore
+    static std::optional<LocalIndexesStats> genLocalIndexStatsByTableInfo(const TiDB::TableInfo & table_info);
 
     bool isCommonHandle() const { return is_common_handle; }
     size_t getRowKeyColumnSize() const { return rowkey_column_size; }

dbms/src/Storages/DeltaMerge/DeltaMergeStore_Statistics.cpp

@@ -193,6 +193,24 @@ SegmentsStats DeltaMergeStore::getSegmentsStats()
     return stats;
 }
 
+std::optional<LocalIndexesStats> DeltaMergeStore::genLocalIndexStatsByTableInfo(const TiDB::TableInfo & table_info)
+{
+    auto local_index_infos = DM::initLocalIndexInfos(table_info, Logger::get());
+    if (!local_index_infos)
+        return std::nullopt;
+
+    DM::LocalIndexesStats stats;
+    for (const auto & index_info : *local_index_infos)
+    {
+        DM::LocalIndexStats index_stats;
+        index_stats.column_id = index_info.column_id;
+        index_stats.index_id = index_info.index_id;
+        index_stats.index_kind = "HNSW";
+        stats.emplace_back(std::move(index_stats));
+    }
+    return stats;
+}
+
 LocalIndexesStats DeltaMergeStore::getLocalIndexStats()
 {
     auto local_index_infos_snap = getLocalIndexInfosSnapshot();

dbms/src/Storages/StorageDeltaMerge.cpp

@@ -1394,16 +1394,24 @@ void StorageDeltaMerge::alterSchemaChange(
     LOG_DEBUG(log, "Update table_info: {} => {}", tidb_table_info.serialize(), table_info.serialize());
 
     {
-        std::lock_guard lock(store_mutex); // Avoid concurrent init store and DDL.
+        // In order to avoid concurrent issue between init store and DDL,
+        // we must acquire the lock before schema changes is applied.
+        std::lock_guard lock(store_mutex);
         if (storeInited())
         {
             _store->applySchemaChanges(table_info);
         }
-        else // it seems we will never come into this branch ?
+        else
         {
+            // If there is no data need to be stored for this table, the _store instance
+            // is not inited to reduce fragmentation files that may exhaust the inode of
+            // disk.
+            // Under this case, we update some in-memory variables to ensure the correctness.
             updateTableColumnInfo();
         }
     }
+
+    // Should generate new decoding snapshot and cache block
     decoding_schema_changed = true;
 
     SortDescription pk_desc = getPrimarySortDescription();

dbms/src/Storages/StorageDeltaMerge.h

@@ -191,25 +191,28 @@ class StorageDeltaMerge
     void checkStatus(const Context & context) override;
     void deleteRows(const Context &, size_t rows) override;
 
+    bool isCommonHandle() const override { return is_common_handle; }
+
+    size_t getRowKeyColumnSize() const override { return rowkey_column_size; }
+
+    DM::DMConfigurationOpt createChecksumConfig() const { return DM::DMChecksumConfig::fromDBContext(global_context); }
+
+public:
     const DM::DeltaMergeStorePtr & getStore() { return getAndMaybeInitStore(); }
 
     DM::DeltaMergeStorePtr getStoreIfInited() const;
 
-    bool isCommonHandle() const override { return is_common_handle; }
-
-    size_t getRowKeyColumnSize() const override { return rowkey_column_size; }
+    bool initStoreIfDataDirExist(ThreadPool * thread_pool) override;
 
+public:
+    /// decoding methods
     std::pair<DB::DecodingStorageSchemaSnapshotConstPtr, BlockUPtr> getSchemaSnapshotAndBlockForDecoding(
         const TableStructureLockHolder & table_structure_lock,
         bool need_block,
         bool with_version_column) override;
 
     void releaseDecodingBlock(Int64 block_decoding_schema_epoch, BlockUPtr block) override;
 
-    bool initStoreIfDataDirExist(ThreadPool * thread_pool) override;
-
-    DM::DMConfigurationOpt createChecksumConfig() const { return DM::DMChecksumConfig::fromDBContext(global_context); }
-
 #ifndef DBMS_PUBLIC_GTEST
 protected:
 #endif
@@ -238,8 +241,12 @@ class StorageDeltaMerge
 
     DataTypePtr getPKTypeImpl() const override;
 
+    // Return the DeltaMergeStore instance
+    // If the instance is not inited, this method will initialize the instance
+    // and return it.
     DM::DeltaMergeStorePtr & getAndMaybeInitStore(ThreadPool * thread_pool = nullptr);
     bool storeInited() const { return store_inited.load(std::memory_order_acquire); }
+
     void updateTableColumnInfo();
     ColumnsDescription getNewColumnsDescription(const TiDB::TableInfo & table_info);
     DM::ColumnDefines getStoreColumnDefines() const override;

dbms/src/Storages/System/StorageSystemDTLocalIndexes.cpp

@@ -21,11 +21,14 @@
 #include <Databases/IDatabase.h>
 #include <Interpreters/Context.h>
 #include <Storages/DeltaMerge/DeltaMergeStore.h>
+#include <Storages/DeltaMerge/Index/LocalIndexInfo.h>
+#include <Storages/KVStore/TMTStorages.h>
 #include <Storages/KVStore/Types.h>
 #include <Storages/MutableSupport.h>
 #include <Storages/StorageDeltaMerge.h>
 #include <Storages/System/StorageSystemDTLocalIndexes.h>
 #include <TiDB/Schema/SchemaNameMapper.h>
+#include <TiDB/Schema/TiDB.h>
 
 namespace DB
 {
@@ -58,6 +61,19 @@ StorageSystemDTLocalIndexes::StorageSystemDTLocalIndexes(const std::string & nam
     }));
 }
 
+std::optional<DM::LocalIndexesStats> getLocalIndexesStatsFromStorage(const StorageDeltaMergePtr & dm_storage)
+{
+    if (dm_storage->isTombstone())
+        return std::nullopt;
+
+    const auto & table_info = dm_storage->getTableInfo();
+    auto store = dm_storage->getStoreIfInited();
+    if (!store)
+        return DM::DeltaMergeStore::genLocalIndexStatsByTableInfo(table_info);
+
+    return store->getLocalIndexStats();
+}
+
 BlockInputStreams StorageSystemDTLocalIndexes::read(
     const Names & column_names,
     const SelectQueryInfo &,
@@ -90,16 +106,12 @@ BlockInputStreams StorageSystemDTLocalIndexes::read(
 
             auto dm_storage = std::dynamic_pointer_cast<StorageDeltaMerge>(storage);
             const auto & table_info = dm_storage->getTableInfo();
-            auto table_id = table_info.id;
-            auto store = dm_storage->getStoreIfInited();
-            if (!store)
-                continue;
+            const auto table_id = table_info.id;
 
-            if (dm_storage->isTombstone())
+            const auto index_stats = getLocalIndexesStatsFromStorage(dm_storage);
+            if (!index_stats)
                 continue;
-
-            auto index_stats = store->getLocalIndexStats();
-            for (auto & stat : index_stats)
+            for (const auto & stat : *index_stats)
             {
                 size_t j = 0;
                 res_columns[j++]->insert(database_name);

dbms/src/TiDB/Schema/tests/gtest_schema_sync.cpp

@@ -52,6 +52,9 @@ extern const char force_context_path[];
 extern const char force_set_num_regions_for_table[];
 extern const char random_ddl_fail_when_rename_partitions[];
 } // namespace FailPoints
+
+// defined in StorageSystemDTLocalIndexes.cpp
+std::optional<DM::LocalIndexesStats> getLocalIndexesStatsFromStorage(const StorageDeltaMergePtr & dm_storage);
 } // namespace DB
 namespace DB::tests
 {
@@ -904,4 +907,121 @@ try
 }
 CATCH
 
+TEST_F(SchemaSyncTest, SyncTableWithVectorIndexCase1)
+try
+{
+    auto pd_client = global_ctx.getTMTContext().getPDClient();
+
+    const String db_name = "mock_db";
+    MockTiDB::instance().newDataBase(db_name);
+
+    auto cols = ColumnsDescription({
+        {"col1", typeFromString("Int64")},
+        {"vec", typeFromString("Array(Float32)")},
+    });
+    auto t1_id = MockTiDB::instance().newTable(db_name, "t1", cols, pd_client->getTS(), "");
+    refreshSchema();
+
+    // The `StorageDeltaMerge` is created but `DeltaMergeStore` is not inited
+    StorageDeltaMergePtr storage = std::static_pointer_cast<StorageDeltaMerge>(mustGetSyncedTable(t1_id));
+    {
+        // The `DeltaMergeStore` is not inited
+        ASSERT_EQ(nullptr, storage->getStoreIfInited());
+        auto stats = getLocalIndexesStatsFromStorage(storage);
+        ASSERT_FALSE(stats.has_value());
+    }
+
+    // add a vector index
+    IndexID idx_id = 11;
+    auto vector_index = std::make_shared<const TiDB::VectorIndexDefinition>(TiDB::VectorIndexDefinition{
+        .kind = tipb::VectorIndexKind::HNSW,
+        .dimension = 3,
+        .distance_metric = tipb::VectorDistanceMetric::L2,
+    });
+    MockTiDB::instance().addVectorIndexToTable(db_name, "t1", idx_id, cols.getAllPhysical().back(), 0, vector_index);
+
+    // sync table schema, the VectorIndex in TableInfo should be updated
+    refreshTableSchema(t1_id);
+    {
+        // The `DeltaMergeStore` is not inited
+        ASSERT_EQ(nullptr, storage->getStoreIfInited());
+        auto stats = getLocalIndexesStatsFromStorage(storage);
+        ASSERT_TRUE(stats.has_value());
+        ASSERT_EQ(stats->size(), 1);
+        auto & s = (*stats)[0];
+        ASSERT_EQ(s.index_id, idx_id);
+        ASSERT_EQ(s.rows_delta_indexed, 0);
+        ASSERT_EQ(s.rows_delta_not_indexed, 0);
+        ASSERT_EQ(s.rows_stable_indexed, 0);
+        ASSERT_EQ(s.rows_stable_not_indexed, 0);
+    }
+
+    auto tbl_info = mustGetSyncedTable(t1_id)->getTableInfo();
+    auto idx_infos = tbl_info.index_infos;
+    ASSERT_EQ(idx_infos.size(), 1);
+    for (const auto & idx : idx_infos)
+    {
+        ASSERT_EQ(idx.id, idx_id);
+        ASSERT_NE(idx.vector_index, nullptr);
+        ASSERT_EQ(idx.vector_index->kind, vector_index->kind);
+        ASSERT_EQ(idx.vector_index->dimension, vector_index->dimension);
+        ASSERT_EQ(idx.vector_index->distance_metric, vector_index->distance_metric);
+    }
+}
+CATCH
+
+TEST_F(SchemaSyncTest, SyncTableWithVectorIndexCase2)
+try
+{
+    auto pd_client = global_ctx.getTMTContext().getPDClient();
+
+    const String db_name = "mock_db";
+    MockTiDB::instance().newDataBase(db_name);
+
+    // The table is created and vector index is added. After that, the table info is synced to TiFlash
+    auto cols = ColumnsDescription({
+        {"col1", typeFromString("Int64")},
+        {"vec", typeFromString("Array(Float32)")},
+    });
+    auto t1_id = MockTiDB::instance().newTable(db_name, "t1", cols, pd_client->getTS(), "");
+    IndexID idx_id = 11;
+    auto vector_index = std::make_shared<const TiDB::VectorIndexDefinition>(TiDB::VectorIndexDefinition{
+        .kind = tipb::VectorIndexKind::HNSW,
+        .dimension = 3,
+        .distance_metric = tipb::VectorDistanceMetric::L2,
+    });
+    MockTiDB::instance().addVectorIndexToTable(db_name, "t1", idx_id, cols.getAllPhysical().back(), 0, vector_index);
+
+    // Synced with mock tidb, and create the StorageDeltaMerge instance
+    refreshTableSchema(t1_id);
+    {
+        // The `DeltaMergeStore` is not inited
+        StorageDeltaMergePtr storage = std::static_pointer_cast<StorageDeltaMerge>(mustGetSyncedTable(t1_id));
+        ASSERT_EQ(nullptr, storage->getStoreIfInited());
+        auto stats = getLocalIndexesStatsFromStorage(storage);
+        ASSERT_TRUE(stats.has_value());
+        ASSERT_EQ(stats->size(), 1);
+        auto & s = (*stats)[0];
+        ASSERT_EQ(s.index_id, idx_id);
+        ASSERT_EQ(s.rows_delta_indexed, 0);
+        ASSERT_EQ(s.rows_delta_not_indexed, 0);
+        ASSERT_EQ(s.rows_stable_indexed, 0);
+        ASSERT_EQ(s.rows_stable_not_indexed, 0);
+    }
+
+
+    auto tbl_info = mustGetSyncedTable(t1_id)->getTableInfo();
+    auto idx_infos = tbl_info.index_infos;
+    ASSERT_EQ(idx_infos.size(), 1);
+    for (const auto & idx : idx_infos)
+    {
+        ASSERT_EQ(idx.id, idx_id);
+        ASSERT_NE(idx.vector_index, nullptr);
+        ASSERT_EQ(idx.vector_index->kind, vector_index->kind);
+        ASSERT_EQ(idx.vector_index->dimension, vector_index->dimension);
+        ASSERT_EQ(idx.vector_index->distance_metric, vector_index->distance_metric);
+    }
+}
+CATCH
+
 } // namespace DB::tests

tests/fullstack-test2/vector/vector-index.test

@@ -16,6 +16,15 @@
 # Preparation.
 mysql> drop table if exists test.t;
 
+# Build vector index on empty table, it should return quickly
+mysql> CREATE TABLE test.t (`v` vector(5) DEFAULT NULL);
+mysql> alter table test.t set tiflash replica 1;
+func> wait_table test t
+mysql> ALTER TABLE test.t ADD VECTOR INDEX idx_v_l2 ((VEC_L2_DISTANCE(v))) USING HNSW;
+mysql> ALTER TABLE test.t ADD VECTOR INDEX idx_v_cos ((VEC_COSINE_DISTANCE(v))) USING HNSW;
+mysql> drop table if exists test.t;
+
+# Build vector index on table with data on the stable layer
 mysql> CREATE TABLE test.t (`v` vector(5) DEFAULT NULL);
 mysql> INSERT INTO test.t VALUES ('[8.7, 5.7, 7.7, 9.8, 1.5]'),('[3.6, 9.7, 2.4, 6.6, 4.9]'),('[4.7, 4.9, 2.6, 5.2, 7.4]'),('[7.7, 6.7, 8.3, 7.8, 5.7]'),('[1.4, 4.5, 8.5, 7.7, 6.2]');
 mysql> alter table test.t set tiflash replica 1;