#pragma once #include #include namespace DB { struct DictionaryStructure; class StorageDictionary final : public ext::shared_ptr_helper, public IStorage { friend struct ext::shared_ptr_helper; public: std::string getName() const override { return "Dictionary"; } void checkTableCanBeDropped() const override; Pipe read( const Names & column_names, const StorageMetadataPtr & /*metadata_snapshot*/, SelectQueryInfo & query_info, const Context & context, QueryProcessingStage::Enum processed_stage, size_t max_block_size, unsigned threads) override; static NamesAndTypesList getNamesAndTypes(const DictionaryStructure & dictionary_structure); static String generateNamesAndTypesDescription(const NamesAndTypesList & list); const String & dictionaryName() const { return dictionary_name; } String resolvedDictionaryName() const; /// Specifies where the table is located relative to the dictionary. enum class Location { /// Table was created automatically as an element of a database with the Dictionary engine. DictionaryDatabase, /// Table was created automatically along with a dictionary /// and has the same database and name as the dictionary. /// It provides table-like access to the dictionary. /// User cannot drop that table. SameDatabaseAndNameAsDictionary, /// Table was created explicitly by a statement like /// CREATE TABLE ... ENGINE=Dictionary /// User chose the table's database and name and can drop that table. Custom, }; private: const String dictionary_name; const Location location; protected: StorageDictionary( const StorageID & table_id_, const String & dictionary_name_, const ColumnsDescription & columns_, Location location_); StorageDictionary( const StorageID & table_id_, const String & dictionary_name_, const DictionaryStructure & dictionary_structure, Location location_); }; }