ClickHouse/dbms/src/Storages/StorageJoin.h
2019-09-09 22:43:37 +03:00

75 lines
2.2 KiB
C++

#pragma once
#include <ext/shared_ptr_helper.h>
#include <Storages/StorageSet.h>
#include <Parsers/ASTTablesInSelectQuery.h>
namespace DB
{
class AnalyzedJoin;
class Join;
using HashJoinPtr = std::shared_ptr<Join>;
/** Allows you save the state for later use on the right side of the JOIN.
* When inserted into a table, the data will be inserted into the state,
* and also written to the backup file, to restore after the restart.
* Reading from the table is not possible directly - only specifying on the right side of JOIN is possible.
*
* When using, JOIN must be of the appropriate type (ANY|ALL LEFT|INNER ...).
*/
class StorageJoin : public ext::shared_ptr_helper<StorageJoin>, public StorageSetOrJoinBase
{
friend struct ext::shared_ptr_helper<StorageJoin>;
public:
String getName() const override { return "Join"; }
void truncate(const ASTPtr &, const Context &, TableStructureWriteLockHolder &) override;
/// Access the innards.
HashJoinPtr & getJoin() { return join; }
/// Verify that the data structure is suitable for implementing this type of JOIN.
void assertCompatible(ASTTableJoin::Kind kind_, ASTTableJoin::Strictness strictness_) const;
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:
Block sample_block;
const Names key_names;
bool use_nulls;
SizeLimits limits;
ASTTableJoin::Kind kind; /// LEFT | INNER ...
ASTTableJoin::Strictness strictness; /// ANY | ALL
std::shared_ptr<AnalyzedJoin> table_join;
HashJoinPtr join;
void insertBlock(const Block & block) override;
size_t getSize() const override;
protected:
StorageJoin(
const String & path_,
const String & database_name_,
const String & table_name_,
const Names & key_names_,
bool use_nulls_,
SizeLimits limits_,
ASTTableJoin::Kind kind_, ASTTableJoin::Strictness strictness_,
const ColumnsDescription & columns_,
const ConstraintsDescription & constraints_,
bool overwrite);
};
}