简单hashjoin mergejoin 完整源码

以下是简单的 Hash Join 的完整源代码（使用 C++ 实现）：

#include <iostream>
#include <unordered_map>
#include <vector>

using namespace std;

struct Record {
    int id;
    string name;
    int age;
};

vector<Record> left_table = {
    {1, "Alice", 20},
    {2, "Bob", 25},
    {3, "Charlie", 30},
    {4, "David", 35},
};

vector<Record> right_table = {
    {101, "Alice", 20},
    {102, "Bob", 25},
    {103, "Eve", 22},
};

void simple_hash_join() {
    // Build a hash table for the left table
    unordered_map<int, Record> ht;
    for (const auto& r : left_table) {
        ht[r.id] = r;
    }

    // Scan the right table and join with the hash table
    for (const auto& r : right_table) {
        auto it = ht.find(r.id);
        if (it != ht.end()) {
            // Join the two records
            const auto& l = it->second;
            cout << l.id << ", " << l.name << ", " << l.age << ", "
                 << r.id << ", " << r.name << ", " << r.age << endl;
        }
    }
}

int main() {
    simple_hash_join();
    return 0;
}

以下是简单的 Merge Join 的完整源代码（使用 C++ 实现）：

#include <iostream>
#include <algorithm>
#include <vector>

using namespace std;

struct Record {
    int id;
    string name;
    int age;
};

vector<Record> left_table = {
    {1, "Alice", 20},
    {2, "Bob", 25},
    {3, "Charlie", 30},
    {4, "David", 35},
};

vector<Record> right_table = {
    {1, "Alice", 20},
    {2, "Bob", 25},
    {3, "Eve", 22},
    {4, "Frank", 40},
};

void simple_merge_join() {
    // Sort both tables by id
    sort(left_table.begin(), left_table.end(), [](const auto& a, const auto& b) {
        return a.id < b.id;
    });
    sort(right_table.begin(), right_table.end(), [](const auto& a, const auto& b) {
        return a.id < b.id;
    });

    // Merge join the two tables
    int i = 0, j = 0;
    while (i < left_table.size() && j < right_table.size()) {
        if (left_table[i].id < right_table[j].id) {
            i++;
        } else if (left_table[i].id > right_table[j].id) {
            j++;
        } else {
            // Join the two records
            const auto& l = left_table[i];
            const auto& r = right_table[j];
            cout << l.id << ", " << l.name << ", " << l.age << ", "
                 << r.id << ", " << r.name << ", " << r.age << endl;

            i++;
            j++;
        }
    }
}

int main() {
    simple_merge_join();
    return 0;
}

以上代码仅供参考，实际应用中需要根据具体情况进行修改和调整。