ddl: Support FLASHBACK DATABASE

dbms/src/Databases/DatabaseTiFlash.cpp

@@ -32,6 +32,7 @@
 #include <Storages/IManageableStorage.h>
 #include <Storages/KVStore/TMTContext.h>
 #include <Storages/KVStore/TMTStorages.h>
+#include <TiDB/Schema/TiDB.h>
 #include <common/logger_useful.h>
 
 namespace DB
@@ -610,7 +611,7 @@ void DatabaseTiFlash::shutdown()
     tables.clear();
 }
 
-void DatabaseTiFlash::alterTombstone(const Context & context, Timestamp tombstone_)
+void DatabaseTiFlash::alterTombstone(const Context & context, Timestamp tombstone_, const TiDB::DBInfoPtr & new_db_info)
 {
     const auto database_metadata_path = getDatabaseMetadataPath(metadata_path);
     const auto database_metadata_tmp_path = database_metadata_path + ".tmp";
@@ -622,7 +623,18 @@ void DatabaseTiFlash::alterTombstone(const Context & context, Timestamp tombston
 
     {
         // Alter the attach statement in metadata.
-        auto dbinfo_literal = std::make_shared<ASTLiteral>(Field(db_info == nullptr ? "" : (db_info->serialize())));
+        std::shared_ptr<ASTLiteral> dbinfo_literal = [&]() {
+            String seri_info;
+            if (new_db_info != nullptr)
+            {
+                seri_info = new_db_info->serialize();
+            }
+            else if (db_info != nullptr)
+            {
+                seri_info = db_info->serialize();
+            }
+            return std::make_shared<ASTLiteral>(Field(seri_info));
+        }();
         Field format_version_field(static_cast<UInt64>(DatabaseTiFlash::CURRENT_VERSION));
         auto version_literal = std::make_shared<ASTLiteral>(format_version_field);
         auto tombstone_literal = std::make_shared<ASTLiteral>(Field(tombstone_));
@@ -651,6 +663,9 @@ void DatabaseTiFlash::alterTombstone(const Context & context, Timestamp tombston
         }
         else
         {
+            // update the seri dbinfo
+            args.children[0] = dbinfo_literal;
+            args.children[1] = version_literal;
             // udpate the tombstone mark
             args.children[2] = tombstone_literal;
         }
@@ -704,6 +719,11 @@ void DatabaseTiFlash::alterTombstone(const Context & context, Timestamp tombston
 
     // After all done, set the tombstone
     tombstone = tombstone_;
+    // Overwrite db_info if not null
+    if (new_db_info)
+    {
+        db_info = new_db_info;
+    }
 }
 
 void DatabaseTiFlash::drop(const Context & context)

dbms/src/Databases/DatabaseTiFlash.h

@@ -89,7 +89,7 @@ class DatabaseTiFlash : public DatabaseWithOwnTablesBase
 
     bool isTombstone() const override { return tombstone != 0; }
     Timestamp getTombstone() const override { return tombstone; }
-    void alterTombstone(const Context & context, Timestamp tombstone_) override;
+    void alterTombstone(const Context & context, Timestamp tombstone_, const TiDB::DBInfoPtr & new_db_info) override;
 
     void drop(const Context & context) override;
 

dbms/src/Databases/IDatabase.h

@@ -24,6 +24,11 @@
 #include <functional>
 #include <memory>
 
+namespace TiDB
+{
+struct DBInfo;
+using DBInfoPtr = std::shared_ptr<DBInfo>;
+} // namespace TiDB
 
 namespace DB
 {
@@ -144,7 +149,11 @@ class IDatabase : public std::enable_shared_from_this<IDatabase>
 
     virtual bool isTombstone() const { return false; }
     virtual Timestamp getTombstone() const { return 0; }
-    virtual void alterTombstone(const Context & /*context*/, Timestamp /*tombstone_*/) {}
+    virtual void alterTombstone(
+        const Context & /*context*/,
+        Timestamp /*tombstone_*/,
+        const TiDB::DBInfoPtr & /*new_db_info*/)
+    {}
 
     /// Delete metadata, the deletion of which differs from the recursive deletion of the directory, if any.
     virtual void drop(const Context & context) = 0;

dbms/src/Databases/test/gtest_database.cpp

@@ -28,10 +28,12 @@
 #include <Storages/IStorage.h>
 #include <Storages/KVStore/TMTContext.h>
 #include <Storages/KVStore/TMTStorages.h>
+#include <Storages/KVStore/Types.h>
 #include <Storages/MutableSupport.h>
 #include <Storages/registerStorages.h>
 #include <TestUtils/TiFlashTestBasic.h>
 #include <TiDB/Schema/SchemaNameMapper.h>
+#include <TiDB/Schema/TiDB.h>
 #include <common/logger_useful.h>
 
 #include <optional>
@@ -942,6 +944,7 @@ try
 )",
     };
 
+    size_t case_no = 0;
     for (const auto & statement : statements)
     {
         {
@@ -968,22 +971,48 @@ try
         LOG_DEBUG(log, "After create [meta={}]", meta);
 
         DB::Timestamp tso = 1000;
-        db->alterTombstone(*ctx, tso);
+        db->alterTombstone(*ctx, tso, nullptr);
         EXPECT_TRUE(db->isTombstone());
         EXPECT_EQ(db->getTombstone(), tso);
+        if (case_no != 0)
+        {
+            auto db_tiflash = std::dynamic_pointer_cast<DatabaseTiFlash>(db);
+            ASSERT_NE(db_tiflash, nullptr);
+            auto db_info = db_tiflash->getDatabaseInfo();
+            ASSERT_EQ(db_info.name, "test_db"); // not changed
+        }
 
         // Try restore from disk
         db = detachThenAttach(*ctx, db_name, std::move(db), log);
         EXPECT_TRUE(db->isTombstone());
         EXPECT_EQ(db->getTombstone(), tso);
 
-        // Recover
-        db->alterTombstone(*ctx, 0);
+        // Recover, usually recover with a new database name
+        auto new_db_info = std::make_shared<TiDB::DBInfo>(
+            R"json({"charset":"utf8mb4","collate":"utf8mb4_bin","db_name":{"L":"test_new_db","O":"test_db"},"id":1010,"state":5})json",
+            NullspaceID);
+        db->alterTombstone(*ctx, 0, new_db_info);
         EXPECT_FALSE(db->isTombstone());
+        if (case_no != 0)
+        {
+            auto db_tiflash = std::dynamic_pointer_cast<DatabaseTiFlash>(db);
+            ASSERT_NE(db_tiflash, nullptr);
+            auto db_info = db_tiflash->getDatabaseInfo();
+            ASSERT_EQ(db_info.name, "test_new_db"); // changed by the `new_db_info`
+        }
 
         // Try restore from disk
         db = detachThenAttach(*ctx, db_name, std::move(db), log);
         EXPECT_FALSE(db->isTombstone());
+        if (case_no != 0)
+        {
+            auto db_tiflash = std::dynamic_pointer_cast<DatabaseTiFlash>(db);
+            ASSERT_NE(db_tiflash, nullptr);
+            auto db_info = db_tiflash->getDatabaseInfo();
+            ASSERT_EQ(db_info.name, "test_new_db"); // changed by the `new_db_info`
+        }
+
+        case_no += 1;
     }
 }
 CATCH

dbms/src/TiDB/Schema/SchemaBuilder.cpp

@@ -259,12 +259,17 @@ void SchemaBuilder<Getter, NameMapper>::applyDiff(const SchemaDiff & diff)
     {
     case SchemaActionType::CreateSchema:
     {
-        applyCreateSchema(diff.schema_id);
+        applyCreateDatabase(diff.schema_id);
         break;
     }
     case SchemaActionType::DropSchema:
     {
-        applyDropSchema(diff.schema_id);
+        applyDropDatabase(diff.schema_id);
+        break;
+    }
+    case SchemaActionType::ActionRecoverSchema:
+    {
+        applyRecoverDatabase(diff.schema_id);
         break;
     }
     case SchemaActionType::CreateTables:
@@ -869,19 +874,19 @@ String createDatabaseStmt(Context & context, const DBInfo & db_info, const Schem
 }
 
 template <typename Getter, typename NameMapper>
-bool SchemaBuilder<Getter, NameMapper>::applyCreateSchema(DatabaseID schema_id)
+bool SchemaBuilder<Getter, NameMapper>::applyCreateDatabase(DatabaseID database_id)
 {
-    auto db_info = getter.getDatabase(schema_id);
-    if (unlikely(db_info == nullptr))
+    auto db_info = getter.getDatabase(database_id);
+    if (db_info == nullptr)
     {
         return false;
     }
-    applyCreateSchema(db_info);
+    applyCreateDatabaseByInfo(db_info);
     return true;
 }
 
 template <typename Getter, typename NameMapper>
-void SchemaBuilder<Getter, NameMapper>::applyCreateSchema(const TiDB::DBInfoPtr & db_info)
+void SchemaBuilder<Getter, NameMapper>::applyCreateDatabaseByInfo(const TiDB::DBInfoPtr & db_info)
 {
     GET_METRIC(tiflash_schema_internal_ddl_count, type_create_db).Increment();
     LOG_INFO(log, "Create database {} begin, database_id={}", name_mapper.debugDatabaseName(*db_info), db_info->id);
@@ -901,29 +906,72 @@ void SchemaBuilder<Getter, NameMapper>::applyCreateSchema(const TiDB::DBInfoPtr
 }
 
 template <typename Getter, typename NameMapper>
-void SchemaBuilder<Getter, NameMapper>::applyDropSchema(DatabaseID schema_id)
+void SchemaBuilder<Getter, NameMapper>::applyRecoverDatabase(DatabaseID database_id)
+{
+    auto db_info = getter.getDatabase(database_id);
+    if (db_info == nullptr)
+    {
+        LOG_INFO(
+            log,
+            "Recover database is ignored because database is not exist in TiKV,"
+            " database_id={}",
+            database_id);
+        return;
+    }
+    LOG_INFO(log, "Recover database begin, database_id={}", database_id);
+    auto db_name = name_mapper.mapDatabaseName(database_id, keyspace_id);
+    auto db = context.tryGetDatabase(db_name);
+    if (!db)
+    {
+        LOG_INFO(
+            log,
+            "Recover database is ignored because instance is not exists, may have been physically dropped, "
+            "database_id={}",
+            db_name,
+            database_id);
+        return;
+    }
+
+    {
+        //TODO: it seems may need a lot time, maybe we can do it in a background thread
+        auto table_ids = table_id_map.findTablesByDatabaseID(database_id);
+        for (auto table_id : table_ids)
+        {
+            auto table_info = getter.getTableInfo(database_id, table_id);
+            applyRecoverLogicalTable(db_info, table_info);
+        }
+    }
+
+    // Usually `FLASHBACK DATABASE ... TO ...` will rename the database
+    db->alterTombstone(context, 0, db_info);
+    databases.addDatabaseInfo(db_info); // add back database info cache
+    LOG_INFO(log, "Recover database end, database_id={}", database_id);
+}
+
+template <typename Getter, typename NameMapper>
+void SchemaBuilder<Getter, NameMapper>::applyDropDatabase(DatabaseID database_id)
 {
-    TiDB::DBInfoPtr db_info = databases.getDBInfo(schema_id);
+    TiDB::DBInfoPtr db_info = databases.getDBInfo(database_id);
     if (unlikely(db_info == nullptr))
     {
-        LOG_INFO(log, "Try to drop database but not found, may has been dropped, database_id={}", schema_id);
+        LOG_INFO(log, "Try to drop database but not found, may has been dropped, database_id={}", database_id);
         return;
     }
 
     {
         //TODO: it seems may need a lot time, maybe we can do it in a background thread
-        auto table_ids = table_id_map.findTablesByDatabaseID(schema_id);
+        auto table_ids = table_id_map.findTablesByDatabaseID(database_id);
         for (auto table_id : table_ids)
-            applyDropTable(schema_id, table_id);
+            applyDropTable(database_id, table_id);
     }
 
-    applyDropSchema(name_mapper.mapDatabaseName(*db_info));
+    applyDropDatabaseByName(name_mapper.mapDatabaseName(database_id, keyspace_id));
 
-    databases.eraseDBInfo(schema_id);
+    databases.eraseDBInfo(database_id);
 }
 
 template <typename Getter, typename NameMapper>
-void SchemaBuilder<Getter, NameMapper>::applyDropSchema(const String & db_name)
+void SchemaBuilder<Getter, NameMapper>::applyDropDatabaseByName(const String & db_name)
 {
     GET_METRIC(tiflash_schema_internal_ddl_count, type_drop_db).Increment();
     LOG_INFO(log, "Tombstone database begin, db_name={}", db_name);
@@ -945,7 +993,7 @@ void SchemaBuilder<Getter, NameMapper>::applyDropSchema(const String & db_name)
     // In such way our database (and its belonging tables) will be GC-ed later than TiDB, which is safe and correct.
     auto & tmt_context = context.getTMTContext();
     auto tombstone = tmt_context.getPDClient()->getTS();
-    db->alterTombstone(context, tombstone);
+    db->alterTombstone(context, tombstone, /*new_db_info*/ nullptr); // keep the old db_info
 
     LOG_INFO(log, "Tombstone database end, db_name={}", db_name);
 }
@@ -1204,7 +1252,7 @@ void SchemaBuilder<Getter, NameMapper>::syncAllSchema()
                 {
                     break;
                 }
-                applyCreateSchema(db_info);
+                applyCreateDatabaseByInfo(db_info);
                 {
                     std::unique_lock<std::mutex> created_db_set_lock(created_db_set_mutex);
                     created_db_set.emplace(name_mapper.mapDatabaseName(*db_info));
@@ -1302,7 +1350,7 @@ void SchemaBuilder<Getter, NameMapper>::syncAllSchema()
         }
         if (created_db_set.count(it->first) == 0 && !isReservedDatabase(context, it->first))
         {
-            applyDropSchema(it->first);
+            applyDropDatabaseByName(it->first);
             LOG_INFO(log, "Database {} dropped during sync all schemas", it->first);
         }
     }
@@ -1474,7 +1522,7 @@ void SchemaBuilder<Getter, NameMapper>::dropAllSchema()
         {
             continue;
         }
-        applyDropSchema(db.first);
+        applyDropDatabaseByName(db.first);
         LOG_INFO(log, "Database {} dropped during drop all schemas", db.first);
     }
 

dbms/src/TiDB/Schema/SchemaBuilder.h

@@ -64,29 +64,29 @@ struct SchemaBuilder
     bool applyTable(DatabaseID database_id, TableID logical_table_id, TableID physical_table_id, bool force);
 
 private:
-    void applyDropSchema(DatabaseID schema_id);
-
+    void applyDropDatabase(DatabaseID database_id);
     /// Parameter db_name should be mapped.
-    void applyDropSchema(const String & db_name);
+    void applyDropDatabaseByName(const String & db_name);
 
-    bool applyCreateSchema(DatabaseID schema_id);
+    bool applyCreateDatabase(DatabaseID database_id);
+    void applyCreateDatabaseByInfo(const TiDB::DBInfoPtr & db_info);
 
-    void applyCreateSchema(const TiDB::DBInfoPtr & db_info);
+    void applyRecoverDatabase(DatabaseID database_id);
 
+    void applyCreateTable(DatabaseID database_id, TableID table_id);
     void applyCreateStorageInstance(
         const TiDB::DBInfoPtr & db_info,
         const TiDB::TableInfoPtr & table_info,
         bool is_tombstone);
 
     void applyDropTable(DatabaseID database_id, TableID table_id);
+    /// Parameter schema_name should be mapped.
+    void applyDropPhysicalTable(const String & db_name, TableID table_id);
 
     void applyRecoverTable(DatabaseID database_id, TiDB::TableID table_id);
     void applyRecoverLogicalTable(const TiDB::DBInfoPtr & db_info, const TiDB::TableInfoPtr & table_info);
     bool tryRecoverPhysicalTable(const TiDB::DBInfoPtr & db_info, const TiDB::TableInfoPtr & table_info);
 
-    /// Parameter schema_name should be mapped.
-    void applyDropPhysicalTable(const String & db_name, TableID table_id);
-
     void applyPartitionDiff(DatabaseID database_id, TableID table_id);
     void applyPartitionDiffOnLogicalTable(
         const TiDB::DBInfoPtr & db_info,
@@ -107,8 +107,6 @@ struct SchemaBuilder
 
     void applySetTiFlashReplica(DatabaseID database_id, TableID table_id);
 
-    void applyCreateTable(DatabaseID database_id, TableID table_id);
-
     void applyExchangeTablePartition(const SchemaDiff & diff);
 };
 

dbms/src/TiDB/Schema/SchemaGetter.cpp

@@ -115,8 +115,7 @@ struct TxnStructure
     static String hGet(KeyspaceSnapshot & snap, const String & key, const String & field)
     {
         String encode_key = encodeHashDataKey(key, field);
-        String value = snap.Get(encode_key);
-        return value;
+        return snap.Get(encode_key);
     }
 
     static String mvccGet(KeyspaceSnapshot & snap, const String & key, const String & field)
@@ -273,7 +272,6 @@ TiDB::DBInfoPtr SchemaGetter::getDatabase(DatabaseID db_id)
 {
     String key = getDBKey(db_id);
     String json = TxnStructure::hGet(snap, DBs, key);
-
     if (json.empty())
         return nullptr;