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/**
* Copyright (C) 2019-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#pragma once
#include <vector>
#include "mongo/db/exec/sbe/stages/stages.h"
#include "mongo/db/exec/sbe/vm/vm.h"
namespace mongo::sbe {
/**
* Performs a traditional hash join. All rows from the 'outer' side are used to construct a hash
* table. Keys from the 'inner' side are used to probe the hash table and produce output rows. This
* is an equality join where the join is defined by equality between the 'outerCond' slot vector on
* the outer side and the 'innerCond' slot vector on the inner side. These two slot vectors must
* have the same length. Each side can define additional slots which appear in each of the rows
* produced by the join, 'outerProjects' and 'innerProjects'.
*
* This is a binding reflector for the outer/build side; since the data is materialized in a hash
* table, stages higher in the tree cannot see any slots lower in the tree on the outer side. This
* is _not_ the case for the inner side, since it can stream data as it probes the hash table.
*
* The optional 'collatorSlot' can be provided to make the join predicate use a special definition
* for string equality. For example, this can be used to perform a case-insensitive join on string
* values.
*
* Debug string representation:
*
* hj collatorSlot?
* left [<outer cond>] [<outer projects>] childStage
* right [<inner cond>] [<inner projects>] childStage
*/
class HashJoinStage final : public PlanStage {
public:
HashJoinStage(std::unique_ptr<PlanStage> outer,
std::unique_ptr<PlanStage> inner,
value::SlotVector outerCond,
value::SlotVector outerProjects,
value::SlotVector innerCond,
value::SlotVector innerProjects,
boost::optional<value::SlotId> collatorSlot,
PlanNodeId planNodeId,
bool participateInTrialRunTracking = true);
std::unique_ptr<PlanStage> clone() const final;
void prepare(CompileCtx& ctx) final;
value::SlotAccessor* getAccessor(CompileCtx& ctx, value::SlotId slot) final;
void open(bool reOpen) final;
PlanState getNext() final;
void close() final;
std::unique_ptr<PlanStageStats> getStats(bool includeDebugInfo) const final;
const SpecificStats* getSpecificStats() const final;
std::vector<DebugPrinter::Block> debugPrint() const final;
size_t estimateCompileTimeSize() const final;
private:
using TableType = std::unordered_multimap<value::MaterializedRow, // NOLINT
value::MaterializedRow,
value::MaterializedRowHasher,
value::MaterializedRowEq>;
using HashKeyAccessor = value::MaterializedRowKeyAccessor<TableType::iterator>;
using HashProjectAccessor = value::MaterializedRowValueAccessor<TableType::iterator>;
const value::SlotVector _outerCond;
const value::SlotVector _outerProjects;
const value::SlotVector _innerCond;
const value::SlotVector _innerProjects;
const boost::optional<value::SlotId> _collatorSlot;
// All defined values from the outer side (i.e. they come from the hash table).
value::SlotAccessorMap _outOuterAccessors;
// Accessors of input condition values (keys) that are being inserted into the hash table.
std::vector<value::SlotAccessor*> _inOuterKeyAccessors;
// Accessors of output keys.
std::vector<std::unique_ptr<HashKeyAccessor>> _outOuterKeyAccessors;
// Accessors of input projection values that are build inserted into the hash table.
std::vector<value::SlotAccessor*> _inOuterProjectAccessors;
// Accessors of output projections.
std::vector<std::unique_ptr<HashProjectAccessor>> _outOuterProjectAccessors;
// Accessors of input condition values (keys) that are being inserted into the hash table.
std::vector<value::SlotAccessor*> _inInnerKeyAccessors;
// Accessor for collator. Only set if collatorSlot provided during construction.
value::SlotAccessor* _collatorAccessor = nullptr;
// Key used to probe inside the hash table.
value::MaterializedRow _probeKey;
boost::optional<TableType> _ht;
TableType::iterator _htIt;
TableType::iterator _htItEnd;
vm::ByteCode _bytecode;
bool _compiled{false};
};
} // namespace mongo::sbe
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