Create ⏱ 12 min

System Design: URL Shortener

What You Will Learn

Design a basic URL shortener system, including its architecture and data model
Understand the trade-offs between URL length and the number of possible unique URLs
Learn how to estimate the number of possible unique URLs for a given character set and URL length

Key Concepts

URL shortener: a service that takes a long URL and converts it to a shorter one
Unique URL: a short URL that points to a specific long URL and is not used by any other long URL
Character set: the set of characters used to generate short URLs, including uppercase and lowercase letters and numbers
URL length: the number of characters in a short URL, which affects the number of possible unique URLs
Database: a storage system used to store the mapping between short and long URLs

Code Examples

No specific code examples are provided in the transcript, but here is a simple example of how a URL shortener might be implemented:

# This is a simple example of a URL shortener, not taken from the transcript
def shorten_url(long_url):
    # Generate a unique short URL
    short_url = generate_short_url()
    # Store the mapping between the short and long URLs
    store_url_mapping(short_url, long_url)
    return short_url

This example illustrates the basic idea of a URL shortener, but is not a real code snippet from the transcript.

Lesson Summary

In this lesson, we learned about the basics of designing a URL shortener system. We started by understanding what a URL shortener is and how it works, including the concept of unique URLs and the trade-offs between URL length and the number of possible unique URLs. We then discussed the key components of a URL shortener system, including the character set, URL length, and database. The instructor explained how to estimate the number of possible unique URLs for a given character set and URL length, using the formula C^N, where C is the number of characters in the character set and N is the number of characters in the short URL. The lesson also touched on the importance of finding a balance between URL length and the number of possible unique URLs, as well as the need to consider the specific requirements of the system being designed.

Practice Exercise

Design a simple URL shortener system that can handle up to 1000 unique URLs. Choose a character set and URL length that will allow you to generate a sufficient number of unique URLs, and explain your reasoning.

What Is Next

In the next lesson, we will continue to explore the design of a URL shortener system, including how to estimate traffic, memory, and bandwidth requirements. We will also discuss how to handle edge cases and errors, and how to optimize the system for performance and scalability.

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