ClickHouse/src/Storages/StorageJoin.h
2022-12-07 15:04:31 +00:00

114 lines
4.3 KiB
C++

#pragma once
#include <Common/RWLock.h>
#include <Storages/StorageSet.h>
#include <Storages/TableLockHolder.h>
#include <Parsers/ASTTablesInSelectQuery.h>
#include <Interpreters/JoinUtils.h>
namespace DB
{
class TableJoin;
class HashJoin;
using HashJoinPtr = std::shared_ptr<HashJoin>;
/** 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 final : public StorageSetOrJoinBase
{
public:
StorageJoin(
DiskPtr disk_,
const String & relative_path_,
const StorageID & table_id_,
const Names & key_names_,
bool use_nulls_,
SizeLimits limits_,
JoinKind kind_,
JoinStrictness strictness_,
const ColumnsDescription & columns_,
const ConstraintsDescription & constraints_,
const String & comment,
bool overwrite,
bool persistent_);
String getName() const override { return "Join"; }
void truncate(const ASTPtr &, const StorageMetadataPtr & metadata_snapshot, ContextPtr, TableExclusiveLockHolder &) override;
/// Only delete is supported.
void checkMutationIsPossible(const MutationCommands & commands, const Settings & settings) const override;
void mutate(const MutationCommands & commands, ContextPtr context) override;
/// Return instance of HashJoin holding lock that protects from insertions to StorageJoin.
/// HashJoin relies on structure of hash table that's why we need to return it with locked mutex.
HashJoinPtr getJoinLocked(std::shared_ptr<TableJoin> analyzed_join, ContextPtr context) const;
/// Get result type for function "joinGet(OrNull)"
DataTypePtr joinGetCheckAndGetReturnType(const DataTypes & data_types, const String & column_name, bool or_null) const;
/// Execute function "joinGet(OrNull)" on data block.
/// Takes rwlock for read to prevent parallel StorageJoin updates during processing data block
/// (but not during processing whole query, it's safe for joinGet that doesn't involve `used_flags` from HashJoin)
ColumnWithTypeAndName joinGet(const Block & block, const Block & block_with_columns_to_add, ContextPtr context) const;
SinkToStoragePtr write(const ASTPtr & query, const StorageMetadataPtr & metadata_snapshot, ContextPtr context) override;
Pipe read(
const Names & column_names,
const StorageSnapshotPtr & storage_snapshot,
SelectQueryInfo & query_info,
ContextPtr context,
QueryProcessingStage::Enum processed_stage,
size_t max_block_size,
size_t num_streams) override;
std::optional<UInt64> totalRows(const Settings & settings) const override;
std::optional<UInt64> totalBytes(const Settings & settings) const override;
Block getRightSampleBlock() const
{
auto metadata_snapshot = getInMemoryMetadataPtr();
Block block = metadata_snapshot->getSampleBlock();
if (use_nulls && isLeftOrFull(kind))
for (auto & col : block)
JoinCommon::convertColumnToNullable(col);
return block;
}
bool useNulls() const { return use_nulls; }
const Names & getKeyNames() const { return key_names; }
private:
Block sample_block;
const Names key_names;
bool use_nulls;
SizeLimits limits;
JoinKind kind; /// LEFT | INNER ...
JoinStrictness strictness; /// ANY | ALL
bool overwrite;
std::shared_ptr<TableJoin> table_join;
HashJoinPtr join;
/// Protect state for concurrent use in insertFromBlock and joinBlock.
/// Lock is stored in HashJoin instance during query and blocks concurrent insertions.
mutable RWLock rwlock = RWLockImpl::create();
mutable std::mutex mutate_mutex;
void insertBlock(const Block & block, ContextPtr context) override;
void finishInsert() override {}
size_t getSize(ContextPtr context) const override;
RWLockImpl::LockHolder tryLockTimedWithContext(const RWLock & lock, RWLockImpl::Type type, ContextPtr context) const;
};
}