mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-10-06 08:30:54 +00:00
40 lines
964 B
C++
40 lines
964 B
C++
#pragma once
|
|
|
|
#include <ext/shared_ptr_helper.h>
|
|
#include <Storages/IStorage.h>
|
|
|
|
|
|
namespace DB
|
|
{
|
|
|
|
class Context;
|
|
|
|
|
|
/** Implements storage for the system table One.
|
|
* The table contains a single column of dummy UInt8 and a single row with a value of 0.
|
|
* Used when the table is not specified in the query.
|
|
* Analog of the DUAL table in Oracle and MySQL.
|
|
*/
|
|
class StorageSystemOne : public ext::shared_ptr_helper<StorageSystemOne>, public IStorage
|
|
{
|
|
public:
|
|
std::string getName() const override { return "SystemOne"; }
|
|
std::string getTableName() const override { return name; }
|
|
|
|
BlockInputStreams read(
|
|
const Names & column_names,
|
|
const SelectQueryInfo & query_info,
|
|
const Context & context,
|
|
QueryProcessingStage::Enum & processed_stage,
|
|
size_t max_block_size,
|
|
unsigned num_streams) override;
|
|
|
|
private:
|
|
const std::string name;
|
|
|
|
protected:
|
|
StorageSystemOne(const std::string & name_);
|
|
};
|
|
|
|
}
|