Optimistic concurrency control in DBMS Theory - Mini Project: Build & Apply

Optimistic Concurrency Control

📖 Scenario: You are managing a simple database system where multiple users can update records. To avoid conflicts, you want to use optimistic concurrency control, which checks if data was changed by someone else before saving updates.

🎯 Goal: Build a step-by-step example showing how optimistic concurrency control works by tracking versions of records and checking them before updates.

📋 What You'll Learn

Create a data structure to hold records with version numbers

Add a variable to represent the current version to check

Write logic to compare versions before updating a record

Complete the process by updating the version after a successful update

💡 Why This Matters

🌍 Real World

Optimistic concurrency control is used in databases and applications where many users may try to update the same data at the same time without locking the data.

💼 Career

Understanding this concept helps in designing systems that handle concurrent data updates efficiently and avoid data conflicts.

1

DATA SETUP: Create records with version numbers

Create a dictionary called records with these exact entries: "item1": {"value": 100, "version": 1} and "item2": {"value": 200, "version": 1}.

DBMS Theory

# Create the records dictionary with initial values and versions
# Your code here

Need a hint?

Use a dictionary where each key is an item name and the value is another dictionary with keys "value" and "version".

2

CONFIGURATION: Set the current version to check

Create a variable called current_version and set it to 1 to represent the version you expect before updating.

DBMS Theory

records = {
    "item1": {"value": 100, "version": 1},
    "item2": {"value": 200, "version": 1}
}
# Set the current_version variable
# Your code here

Need a hint?

This variable holds the version number you expect the record to have before updating.

3

CORE LOGIC: Check version before updating

Write an if statement that compares records["item1"]["version"] with current_version. If they are equal, update records["item1"]["value"] to 150.

DBMS Theory

records = {
    "item1": {"value": 100, "version": 1},
    "item2": {"value": 200, "version": 1}
}
current_version = 1
# Check version and update value if versions match
# Your code here

Need a hint?

Use an if statement to compare the version before changing the value.

4

COMPLETION: Update the version after successful update

Inside the if block, add a line to increase records["item1"]["version"] by 1 to reflect the new version after update.

DBMS Theory

records = {
    "item1": {"value": 100, "version": 1},
    "item2": {"value": 200, "version": 1}
}
current_version = 1
if records["item1"]["version"] == current_version:
    records["item1"]["value"] = 150
    # Increase the version number here
    # Your code here

Need a hint?

Increment the version number by 1 after updating the value.