ClickHouse/dbms/src/Storages/System/StorageSystemNumbers.h
2017-05-25 00:06:29 +03:00

46 lines
1.2 KiB
C++

#pragma once
#include <ext/shared_ptr_helper.hpp>
#include <Storages/IStorage.h>
namespace DB
{
class Context;
/** Implements a repository for the system table Numbers.
* The table contains the only column number UInt64.
* From this table, you can read all natural numbers, starting from 0 (to 2^64 - 1, and then again).
*/
class StorageSystemNumbers : private ext::shared_ptr_helper<StorageSystemNumbers>, public IStorage
{
friend class ext::shared_ptr_helper<StorageSystemNumbers>;
public:
static StoragePtr create(const std::string & name_, bool multithreaded_ = false);
std::string getName() const override { return "SystemNumbers"; }
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,
QueryProcessingStage::Enum & processed_stage,
size_t max_block_size = DEFAULT_BLOCK_SIZE,
unsigned threads = 1) override;
private:
const std::string name;
NamesAndTypesList columns;
bool multithreaded;
StorageSystemNumbers(const std::string & name_, bool multithreaded_);
};
}