ClickHouse/dbms/include/DB/Storages/StorageSystemNumbers.h
2012-05-30 04:45:49 +00:00

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#pragma once
#include <Poco/SharedPtr.h>
#include <DB/Storages/IStorage.h>
#include <DB/DataStreams/IProfilingBlockInputStream.h>
namespace DB
{
using Poco::SharedPtr;
class NumbersBlockInputStream : public IProfilingBlockInputStream
{
public:
NumbersBlockInputStream(size_t block_size_);
Block readImpl();
String getName() const { return "NumbersBlockInputStream"; }
BlockInputStreamPtr clone() { return new NumbersBlockInputStream(block_size); }
private:
size_t block_size;
UInt64 next;
};
/** Реализует хранилище для системной таблицы Numbers.
* Таблица содержит единственный столбец number UInt64.
* Из этой таблицы можно прочитать все натуральные числа, начиная с 0 (до 2^64 - 1, а потом заново).
*/
class StorageSystemNumbers : public IStorage
{
public:
StorageSystemNumbers(const std::string & name_);
std::string getName() const { return "SystemNumbers"; }
std::string getTableName() const { return name; }
const NamesAndTypesList & getColumnsList() const { return columns; }
BlockInputStreams read(
const Names & column_names,
ASTPtr query,
QueryProcessingStage::Enum & processed_stage,
size_t max_block_size = DEFAULT_BLOCK_SIZE,
unsigned threads = 1);
private:
const std::string name;
NamesAndTypesList columns;
};
}