Deep Dive Toolkit
A Bloom filter is a memory-efficient way to answer one question: “Have we maybe seen this item before?” It is useful when you want to avoid expensive lookups for items that definitely do not exist. The simple idea A Bloom filter is a probabilistic data structure. It can answer: Definitely
Deep Dive Toolkit
Concurrency control is about one simple question: what happens when two requests try to change the same data at the same time? In interviews, this topic shows up in booking, inventory, payments, orders, auctions, and job scheduling. The problem Many systems have shared resources. Examples: * two users try to book
Core Building Blocks
Core Building Blocks
Core Building Blocks
Blob storage is used for large files such as images, videos, PDFs, logs, and backups. In interviews, the most common pattern is simple: store metadata in the database, and store the actual file in object storage. What blob storage is Blob storage, also called object storage, stores unstructured binary data.
Core Building Blocks
A message queue helps you move slow or unreliable work out of the main request path. In interviews, it is one of the clearest ways to improve latency, reliability, and system flexibility. What a message queue does A message queue lets one service send a task or event to another
Core Building Blocks
A CDN helps users download content from servers close to them. In interviews, CDN is usually the right tool for static files, images, videos, and other content that can be cached at the edge. What a CDN does CDN means Content Delivery Network. It is a network of edge servers
Core Building Blocks
A cache is a fast storage layer used to reduce latency and database load. In system design interviews, cache is one of the most common tools, but you should only use it when the read pattern makes sense. What a cache does A cache stores frequently accessed data in memory.
Core Building Blocks
Your job is not to name a database randomly. Your job is to explain what data you need to store, how you will query it, and what consistency you need. What a database does A database stores the main business data of your system. Examples: * users * orders * payments * posts * messages
Quick Start
Quick Start
Quick Start
Most candidates do not fail system design interviews because they do not know enough technologies. They fail because their answer is unclear, unstructured, or too shallow. Mistake 1: Starting with a diagram too early Many candidates hear the prompt and immediately start drawing boxes. This is risky. If you do