ClickHouse/dbms/include/DB/Storages/System/StorageSystemColumns.h

42 lines
1.0 KiB
C++

#pragma once
#include <ext/shared_ptr_helper.hpp>
#include <DB/Storages/IStorage.h>
namespace DB
{
class Context;
/** Implements system table 'columns', that allows to get information about columns for every table.
*/
class StorageSystemColumns : private ext::shared_ptr_helper<StorageSystemColumns>, public IStorage
{
friend class ext::shared_ptr_helper<StorageSystemColumns>;
public:
static StoragePtr create(const std::string & name_);
std::string getName() const override { return "SystemColumns"; }
std::string getTableName() const override { return name; }
const NamesAndTypesList & getColumnsListImpl() const override { return columns; }
BlockInputStreams read(
const Names & column_names,
ASTPtr query,
const Context & context,
const Settings & settings,
QueryProcessingStage::Enum & processed_stage,
size_t max_block_size = DEFAULT_BLOCK_SIZE,
unsigned threads = 1) override;
private:
StorageSystemColumns(const std::string & name_);
private:
const std::string name;
NamesAndTypesList columns;
};
}