Database Concurrency Control Example

This project demonstrates a simple example of implementing database concurrency control using Sequelize in a Node.js/Express application with a MySQL database.

Table of Contents

• Introduction
• Prerequisites
• Getting Started
• Understanding Database Concurrency Control
• Executing the Script
• Additional Notes

Introduction

This project showcases a Node.js/Express application that interacts with a MySQL database using Sequelize. The application includes a basic API endpoint (POST /) that increments a counter in the database.

Prerequisites

Before running the application, make sure you have the following installed:

• Node.js
• npm (Node Package Manager)
• MySQL
• Sequelize

Getting Started

1. Clone the repository:

   git clone https://github.com/your-username/your-repo.git

2. Install dependencies:

   cd your-repo
   npm install

3. Configure the database credentials:

   Open TSroute.ts and replace the placeholder values with your actual database credentials:

   const sequelize = new Sequelize('your-database', 'your-username', 'your-password', {
       host: 'localhost',
       dialect: 'mysql',
   });

4. Sync the model with the database:

   npm run sync

5. Initialize the database with an initial count value:

   Open TSroute.ts and find the following code:

   // Add this code to initialize the database with a starting count value
   const initialCount = 10;
   await Count.create({ count: initialCount });

6. Insert SQL script:

   -- Add this SQL command to initialize the database with a starting count value
   INSERT INTO counts (count) VALUES (10);

7. Save the changes and run the script:

   npx ts-node src/app/server.ts

Understanding Database Concurrency Control

The main file TSroute.ts includes a POST endpoint that increments a counter in the database. It uses Sequelize for database interactions.

1. The Count model is defined with two columns: id (primary key) and count.
2. The POST endpoint finds the row with id = 1, increments the count value, and updates the database.

Executing the Script

To execute the script that simulates 1000 POST requests:

chmod +x execute_1000_times.sh
./execute_1000_times.sh