Question: Is DynamoDB a relational database?

Answer

No. Amazon DynamoDB is a NoSQL key-value and document database, not a relational database. Its tables contain items with flexible attributes, including nested maps and lists. Only the primary key needs a declared schema; other attributes can differ between items.

The word "table" does not make DynamoDB relational. In MySQL or PostgreSQL, you commonly normalize data into related tables and join them at query time. In DynamoDB, you choose partition keys, sort keys and indexes around the application's access patterns. Related records can share a partition key, or you can duplicate selected data to answer a request without a join.

DynamoDB does support PartiQL, a SQL-compatible interface for reading and writing items. That syntax does not turn it into a SQL database: DynamoDB's implementation has no relational joins, foreign-key constraints or general-purpose SQL aggregation. A statement without a suitable key condition can still scan the table.

NoSQL also does not mean "no transactions." DynamoDB has atomic item operations and ACID transactions across items and tables within one account and Region. Read consistency and transaction isolation are separate choices from the data model.

Choose DynamoDB when the important lookups are known and can be expressed through keys and indexes. A relational database is often easier when you need changing ad hoc queries, joins and database-enforced relationships. See DynamoDB vs Amazon RDS and modeling relationships without joins.

Source: AWS PartiQL documentation.