beedb/include/execution/hash_join_operator.h

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2022-04-04 20:25:01 +02:00
/*------------------------------------------------------------------------------*
* Architecture & Implementation of DBMS *
*------------------------------------------------------------------------------*
* Copyright 2022 Databases and Information Systems Group TU Dortmund *
* Visit us at *
* http://dbis.cs.tu-dortmund.de/cms/en/home/ *
* *
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS *
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, *
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL *
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR *
* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, *
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR *
* OTHER DEALINGS IN THE SOFTWARE. *
* *
* Authors: *
* Maximilian Berens <maximilian.berens@tu-dortmund.de> *
* Roland Kühn <roland.kuehn@cs.tu-dortmund.de> *
* Jan Mühlig <jan.muehlig@tu-dortmund.de> *
*------------------------------------------------------------------------------*
*/
#pragma once
#include "binary_operator.h"
#include "tuple_buffer.h"
#include <memory>
#include <string>
#include <table/memory_table.h>
#include <table/schema.h>
#include <table/tuple.h>
#include <unordered_map>
#include <utility>
#include <vector>
namespace beedb::execution
{
/**
* Hash table for hash join.
*/
class HashTable
{
public:
explicit HashTable(const std::uint32_t key_index) : _key_index(key_index)
{
}
~HashTable() = default;
bool contains(const table::Value &key)
{
return this->_map.find(key) != _map.end();
}
void put(const table::Tuple &tuple)
{
table::Tuple in_memory_tuple(tuple);
this->_map[tuple.get(_key_index)].push_back(std::move(in_memory_tuple));
}
const std::vector<table::Tuple> &get(const table::Value &key)
{
return _map[key];
}
private:
const std::uint32_t _key_index;
std::unordered_map<table::Value, std::vector<table::Tuple>> _map;
};
/**
* Operator that joins two sources using a hash table over
* the left source.
*/
class HashJoinOperator final : public BinaryOperator
{
public:
HashJoinOperator(concurrency::Transaction *transaction, table::Schema &&schema, const std::uint32_t left_index,
const std::uint32_t right_index);
~HashJoinOperator() override = default;
void open() override;
util::optional<table::Tuple> next() override;
void close() override;
[[nodiscard]] const table::Schema &schema() const override
{
return _schema;
}
private:
const table::Schema _schema;
const std::uint32_t _left_index;
const std::uint32_t _right_index;
HashTable _hash_table;
bool _is_built = false;
TupleBuffer _tuple_buffer;
/**
* Builds the hash table.
*/
void build_hash_table();
/**
* Probes the hash table.
*/
util::optional<table::Tuple> probe_hash_table();
};
} // namespace beedb::execution