Core Concepts

Understanding DynamoDB's core concepts is essential before you start building. This lesson covers tables, items, attributes, primary keys, and data types — the fundamental building blocks of every DynamoDB application.

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Tables

A table is the top-level container for data in DynamoDB, similar to a table in a relational database:

• Each table has a name that must be unique within an AWS account and Region
• Tables are schemaless — only the primary key attributes must be defined upfront
• Non-key attributes can vary from item to item
• There is no practical limit on the number of items a table can store
• Table storage grows automatically as you add data

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Items

An item is a single record in a table, similar to a row in a relational database:

• Each item is uniquely identified by its primary key
• An item is a collection of attributes
• Maximum item size is 400 KB (including attribute names and values)
• Items in the same table can have completely different attributes

Example Items in a Users Table

{
  "UserId": "user-001",
  "Name": "Alice",
  "Email": "alice@example.com",
  "Age": 30
}