ClickHouse/dbms/Storages/StorageMemory.h
2020-04-03 03:19:11 +03:00

59 lines
1.6 KiB
C++

#pragma once
#include <mutex>
#include <ext/shared_ptr_helper.h>
#include <Core/NamesAndTypes.h>
#include <Storages/IStorage.h>
#include <DataStreams/IBlockOutputStream.h>
namespace DB
{
/** Implements storage in the RAM.
* Suitable for temporary data.
* It does not support keys.
* Data is stored as a set of blocks and is not stored anywhere else.
*/
class StorageMemory final : public ext::shared_ptr_helper<StorageMemory>, public IStorage
{
friend class MemoryBlockInputStream;
friend class MemoryBlockOutputStream;
friend struct ext::shared_ptr_helper<StorageMemory>;
public:
String getName() const override { return "Memory"; }
size_t getSize() const { return data.size(); }
Pipes 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;
BlockOutputStreamPtr write(const ASTPtr & query, const Context & context) override;
void drop() override;
void truncate(const ASTPtr &, const Context &, TableStructureWriteLockHolder &) override;
std::optional<UInt64> totalRows() const override;
std::optional<UInt64> totalBytes() const override;
private:
/// The data itself. `list` - so that when inserted to the end, the existing iterators are not invalidated.
BlocksList data;
mutable std::mutex mutex;
protected:
StorageMemory(const StorageID & table_id_, ColumnsDescription columns_description_, ConstraintsDescription constraints_);
};
}