DynamoDB

Opening Scenario

You're building a session store for a social app. At peak: 50,000 requests per second. Sessions are keyed by a session ID, each request reads or writes a single session. Query patterns are simple — always by session ID, never by email or timestamp. The data per item is small. But you need single-digit millisecond latency at any scale, with no database server to manage. A relational database on a single instance won't handle this traffic. What do you reach for?

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Question Progression

Concept 1: What is DynamoDB's data model and how is it different from a relational database?

Question You're used to tables with rows, columns, foreign keys, and joins. DynamoDB is also described as having "tables" and "items." What's actually different?

Reasoning The word "table" is shared, but the underlying model is radically different. Understanding this distinction prevents the most common DynamoDB design mistakes.

Answer DynamoDB…