animation/nested_loop_with_index.html at main · enhancedformysql/animation · GitHub

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<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>MySQL Nested Loop Join with Index Visualization</title>
    <style>
        body {
            font-family: Arial, sans-serif;
            margin: 20px;
        }
        .container {
            display: flex;
            justify-content: space-between;
            margin-bottom: 20px;
        }
        .table-container {
            width: 45%;
            border: 1px solid #ddd;
            padding: 10px;
            border-radius: 5px;
            position: relative;
        }
        .result-container {
            width: 100%;
            border: 1px solid #ddd;
            padding: 10px;
            border-radius: 5px;
            margin-top: 20px;
            min-height: 100px;
        }
        table {
            width: 100%;
            border-collapse: collapse;
        }
        th, td {
            border: 1px solid #ddd;
            padding: 8px;
            text-align: left;
        }
        th {
            background-color: #f2f2f2;
        }
        .highlight {
            background-color: #ffeb3b;
            transition: background-color 0.3s;
        }
        .matched {
            background-color: #a5d6a7;
            transition: background-color 0.3s;
        }
        .index-used {
            background-color: #90caf9;
            transition: background-color 0.3s;
        }
        .controls {
            margin: 20px 0;
        }
        button {
            padding: 8px 16px;
            margin-right: 10px;
            cursor: pointer;
        }
        .arrow {
            position: absolute;
            width: 100px;
            height: 2px;
            background-color: red;
            top: 50%;
            left: 50%;
            transform-origin: left center;
            display: none;
        }
        .arrow::after {
            content: '';
            position: absolute;
            right: 0;
            top: -4px;
            width: 0;
            height: 0;
            border-left: 8px solid red;
            border-top: 5px solid transparent;
            border-bottom: 5px solid transparent;
        }
        .explanation {
            margin: 20px 0;
            padding: 15px;
            background-color: #f8f9fa;
            border-radius: 5px;
        }
        .index-visual {
            position: absolute;
            right: 10px;
            top: 50px;
            border: 1px dashed #aaa;
            padding: 5px;
            background-color: #fff;
            display: none;
        }
        .toggle-container {
            margin: 10px 0;
        }
        .performance-metrics {
            margin-top: 20px;
            padding: 10px;
            background-color: #e8f5e9;
            border-radius: 5px;
        }
    </style>
</head>
<body>
    <h1>MySQL Nested Loop Join with Index Visualization</h1>

    <div class="explanation">
        <h3>How Indexes Affect Nested Loop Joins:</h3>
        <ol>
            <li><strong>Without Index</strong>: Inner table requires full scan for each outer row (O(M*N))</li>
            <li><strong>With Index</strong>: Database can directly locate matching rows using the index (O(M*log N))</li>
            <li>The join column (dept_id) should be indexed in the inner table for this optimization</li>
        </ol>
    </div>

    <div class="toggle-container">
        <label>
            <input type="checkbox" id="useIndexCheckbox"> Use Index on Department ID
        </label>
    </div>

    <div class="controls">
        <button id="startBtn">Start Animation</button>
        <button id="resetBtn">Reset</button>
        <button id="stepBtn">Step Through</button>
        <div>
            <label>Animation Speed: </label>
            <input type="range" id="speedSlider" min="100" max="2000" value="500">
            <span id="speedValue">500ms</span>
        </div>
    </div>

    <div class="container">
        <div class="table-container" id="outerTableContainer">
            <h3>Outer Table (Driving Table) - Employees</h3>
            <table id="outerTable">
                <thead>
                    <tr>
                        <th>id</th>
                        <th>name</th>
                        <th>dept_id</th>
                    </tr>
                </thead>
                <tbody>
                    <tr data-id="1">
                        <td>1</td>
                        <td>Alice</td>
                        <td>101</td>
                    </tr>
                    <tr data-id="2">
                        <td>2</td>
                        <td>Bob</td>
                        <td>102</td>
                    </tr>
                    <tr data-id="3">
                        <td>3</td>
                        <td>Charlie</td>
                        <td>101</td>
                    </tr>
                    <tr data-id="4">
                        <td>4</td>
                        <td>David</td>
                        <td>103</td>
                    </tr>
                </tbody>
            </table>
        </div>

        <div class="table-container" id="innerTableContainer">
            <h3>Inner Table (Driven Table) - Departments</h3>
            <div class="index-visual" id="indexVisual">
                <strong>Index on dept_id</strong><br>
                101 ¡ú Row 1<br>
                102 ¡ú Row 2<br>
                103 ¡ú Row 3
            </div>
            <table id="innerTable">
                <thead>
                    <tr>
                        <th>dept_id</th>
                        <th>dept_name</th>
                    </tr>
                </thead>
                <tbody>
                    <tr data-id="101">
                        <td>101</td>
                        <td>Engineering</td>
                    </tr>
                    <tr data-id="102">
                        <td>102</td>
                        <td>Marketing</td>
                    </tr>
                    <tr data-id="103">
                        <td>103</td>
                        <td>Finance</td>
                    </tr>
                </tbody>
            </table>
        </div>
    </div>

    <div class="result-container">
        <h3>Join Result (employees JOIN departments ON dept_id)</h3>
        <table id="resultTable">
            <thead>
                <tr>
                    <th>emp_id</th>
                    <th>emp_name</th>
                    <th>dept_id</th>
                    <th>dept_name</th>
                </tr>
            </thead>
            <tbody></tbody>
        </table>
    </div>

    <div class="performance-metrics">
        <h3>Performance Metrics</h3>
        <p>Inner Table Scans: <span id="scanCount">0</span></p>
        <p>Index Lookups: <span id="indexLookupCount">0</span></p>
        <p>Rows Processed: <span id="rowsProcessed">0</span></p>
    </div>

    <div class="arrow" id="arrow"></div>

    <script>
        const outerTable = document.getElementById('outerTable');
        const innerTable = document.getElementById('innerTable');
        const resultTable = document.getElementById('resultTable').querySelector('tbody');
        const startBtn = document.getElementById('startBtn');
        const resetBtn = document.getElementById('resetBtn');
        const stepBtn = document.getElementById('stepBtn');
        const speedSlider = document.getElementById('speedSlider');
        const speedValue = document.getElementById('speedValue');
        const arrow = document.getElementById('arrow');
        const useIndexCheckbox = document.getElementById('useIndexCheckbox');
        const indexVisual = document.getElementById('indexVisual');
        const scanCountElement = document.getElementById('scanCount');
        const indexLookupCountElement = document.getElementById('indexLookupCount');
        const rowsProcessedElement = document.getElementById('rowsProcessed');

        let outerRows = Array.from(outerTable.querySelectorAll('tbody tr'));
        let innerRows = Array.from(innerTable.querySelectorAll('tbody tr'));
        let currentOuterIndex = 0;
        let currentInnerIndex = 0;
        let isRunning = false;
        let animationInterval;
        let speed = 500;
        let useIndex = false;
        let scanCount = 0;
        let indexLookupCount = 0;
        let rowsProcessed = 0;

        // Initialize index visualization
        useIndexCheckbox.addEventListener('change', function() {
            useIndex = this.checked;
            indexVisual.style.display = useIndex ? 'block' : 'none';
            resetAnimation();
        });

        speedSlider.addEventListener('input', function() {
            speed = parseInt(this.value);
            speedValue.textContent = speed + 'ms';
            if (isRunning) {
                clearInterval(animationInterval);
                startAnimation();
            }
        });

        startBtn.addEventListener('click', function() {
            if (!isRunning) {
                startAnimation();
            } else {
                pauseAnimation();
            }
        });

        resetBtn.addEventListener('click', resetAnimation);
        stepBtn.addEventListener('click', stepAnimation);

        function startAnimation() {
            isRunning = true;
            startBtn.textContent = 'Pause';
            animationInterval = setInterval(stepAnimation, speed);
        }

        function pauseAnimation() {
            isRunning = false;
            startBtn.textContent = 'Resume';
            clearInterval(animationInterval);
        }

        function resetAnimation() {
            pauseAnimation();

            // Reset highlights
            outerRows.forEach(row => row.classList.remove('highlight'));
            innerRows.forEach(row => row.classList.remove('matched', 'highlight', 'index-used'));

            // Clear result table
            resultTable.innerHTML = '';

            // Reset pointers
            currentOuterIndex = 0;
            currentInnerIndex = 0;

            // Reset metrics
            scanCount = 0;
            indexLookupCount = 0;
            rowsProcessed = 0;
            updateMetrics();

            // Hide arrow
            arrow.style.display = 'none';
        }

        function updateMetrics() {
            scanCountElement.textContent = scanCount;
            indexLookupCountElement.textContent = indexLookupCount;
            rowsProcessedElement.textContent = rowsProcessed;
        }

        function stepAnimation() {
            // Clear previous highlights
            outerRows.forEach(row => row.classList.remove('highlight'));
            innerRows.forEach(row => row.classList.remove('matched', 'highlight', 'index-used'));

            // If we've processed all outer rows, finish
            if (currentOuterIndex >= outerRows.length) {
                pauseAnimation();
                return;
            }

            // Highlight current outer row
            const currentOuterRow = outerRows[currentOuterIndex];
            currentOuterRow.classList.add('highlight');
            rowsProcessed++;

            // Show arrow from outer to inner table
            const outerRect = currentOuterRow.getBoundingClientRect();
            const innerContainerRect = document.getElementById('innerTableContainer').getBoundingClientRect();

            arrow.style.display = 'block';
            arrow.style.left = (outerRect.right + 10) + 'px';
            arrow.style.top = (outerRect.top + outerRect.height / 2) + 'px';
            arrow.style.width = (innerContainerRect.left - outerRect.right - 20) + 'px';

            // Get outer row's dept_id
            const outerDeptId = currentOuterRow.querySelector('td:nth-child(3)').textContent;

            if (useIndex) {
                // With index - direct lookup
                const matchingInnerRow = innerRows.find(row => row.getAttribute('data-id') === outerDeptId);

                if (matchingInnerRow) {
                    indexLookupCount++;
                    matchingInnerRow.classList.add('index-used', 'matched');

                    // Add to result table
                    const newRow = document.createElement('tr');
                    newRow.innerHTML = `
                        <td>${currentOuterRow.querySelector('td:nth-child(1)').textContent}</td>
                        <td>${currentOuterRow.querySelector('td:nth-child(2)').textContent}</td>
                        <td>${outerDeptId}</td>
                        <td>${matchingInnerRow.querySelector('td:nth-child(2)').textContent}</td>
                    `;
                    resultTable.appendChild(newRow);
                }

                // Move to next outer row immediately
                currentOuterIndex++;
                currentInnerIndex = 0;
            } else {
                // Without index - full scan

                // If we've scanned all inner rows, move to next outer row
                if (currentInnerIndex >= innerRows.length) {
                    scanCount++;
                    currentOuterIndex++;
                    currentInnerIndex = 0;
                    return;
                }

                // Highlight current inner row
                const currentInnerRow = innerRows[currentInnerIndex];
                currentInnerRow.classList.add('highlight');
                rowsProcessed++;

                // Get inner row's dept_id
                const innerDeptId = currentInnerRow.querySelector('td:first-child').textContent;

                // Check for match
                if (outerDeptId === innerDeptId) {
                    currentInnerRow.classList.add('matched');

                    // Add to result table
                    const newRow = document.createElement('tr');
                    newRow.innerHTML = `
                        <td>${currentOuterRow.querySelector('td:nth-child(1)').textContent}</td>
                        <td>${currentOuterRow.querySelector('td:nth-child(2)').textContent}</td>
                        <td>${outerDeptId}</td>
                        <td>${currentInnerRow.querySelector('td:nth-child(2)').textContent}</td>
                    `;
                    resultTable.appendChild(newRow);
                }

                // Move to next inner row
                currentInnerIndex++;

                // If we've finished scanning inner table, move to next outer row
                if (currentInnerIndex >= innerRows.length) {
                    setTimeout(() => {
                        scanCount++;
                        currentOuterIndex++;
                        currentInnerIndex = 0;
                    }, speed / 2);
                }
            }

            updateMetrics();
        }

        // Initialize
        resetAnimation();
    </script>
</body>
</html>