Timestamp-based protocols in DBMS Theory - Mini Project: Build & Apply

Timestamp-based Protocols in Database Management

📖 Scenario: You are managing a simple database system that uses timestamp-based protocols to control transaction order and avoid conflicts.Each transaction has a unique timestamp, and the system uses these timestamps to decide whether to allow or reject read and write operations.

🎯 Goal: Build a basic SQL setup that models timestamp-based concurrency control by creating a table for transactions with timestamps, setting a current timestamp variable, and writing queries that check if transactions can proceed based on their timestamps.

📋 What You'll Learn

Create a table named transactions with columns transaction_id (integer) and timestamp (integer).

Create a variable named current_timestamp and set it to 100.

Write a query that selects all transactions with a timestamp less than current_timestamp.

Write a query that selects all transactions with a timestamp greater than or equal to current_timestamp.

💡 Why This Matters

🌍 Real World

Timestamp-based protocols help databases manage multiple transactions safely by ordering them using timestamps to avoid conflicts.

💼 Career

Understanding timestamp-based concurrency control is important for database administrators and developers to ensure data consistency and avoid errors in multi-user environments.

1

Create the transactions table

Create a table called transactions with two columns: transaction_id as INTEGER and timestamp as INTEGER.

DBMS Theory

-- Your code here to create the transactions table

Need a hint?

Use CREATE TABLE statement with the specified column names and types.

2

Set the current timestamp variable

Create a variable named current_timestamp and set it to 100. Use a SQL variable declaration or assignment suitable for your SQL environment.

DBMS Theory

CREATE TABLE transactions (
    transaction_id INTEGER,
    timestamp INTEGER
);
-- Your code here to set current_timestamp to 100

Need a hint?

Use SET @current_timestamp = 100; to declare and assign the variable.

3

Select transactions with timestamp less than current_timestamp

Write a SQL query to select all columns from transactions where timestamp is less than @current_timestamp.

DBMS Theory

CREATE TABLE transactions (
    transaction_id INTEGER,
    timestamp INTEGER
);

-- Setting current_timestamp variable
SET @current_timestamp = 100;
-- Your code here to select transactions with timestamp less than current_timestamp

Need a hint?

Use a SELECT statement with a WHERE clause comparing timestamp and @current_timestamp.

4

Select transactions with timestamp greater than or equal to current_timestamp

Write a SQL query to select all columns from transactions where timestamp is greater than or equal to @current_timestamp.

DBMS Theory

CREATE TABLE transactions (
    transaction_id INTEGER,
    timestamp INTEGER
);

-- Setting current_timestamp variable
SET @current_timestamp = 100;

SELECT * FROM transactions WHERE timestamp = current_timestamp

Need a hint?

Use a SELECT statement with a WHERE clause using the >= operator.