ClickHouse/src/Storages/StorageDictionary.h
2020-07-05 18:45:05 +03:00

70 lines
2.1 KiB
C++

#pragma once
#include <Storages/IStorage.h>
#include <ext/shared_ptr_helper.h>
namespace DB
{
struct DictionaryStructure;
class StorageDictionary final : public ext::shared_ptr_helper<StorageDictionary>, public IStorage
{
friend struct ext::shared_ptr_helper<StorageDictionary>;
public:
std::string getName() const override { return "Dictionary"; }
void checkTableCanBeDropped() const override;
Pipes read(
const Names & column_names,
const StorageMetadataPtr & /*metadata_snapshot*/,
const 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; }
/// 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_);
};
}