Amazon DynamoDB vs PostgreSQL

Amazon DynamoDB is a serverless, managed NoSQL database for applications that need single-digit millisecond performance at any scale, according to AWS. Users do not provision or patch database servers, and tables can scale automatically, including to zero in on-demand mode. Primary keys and global or local secondary indexes provide ways to query data. Global tables support multi-Region, multi-active operation; AWS says they are designed for up to 99.999% availability. The database also supports native vector search for similarity searches and agent memory use cases. Data is encrypted in transit and at rest by default, and IAM policies can restrict access to specific items and attributes. Point-in-time recovery provides continuous, per-second backups and restoration within a configured period of 1 to 35 days. A free tier is listed with 25 WCUs, 25 RCUs, and 25 GB of storage per Region and payer account, among other limits. On-demand capacity is billed per request consumed; provisioned capacity is billed for specified capacity even if usage is lower.

PostgreSQL is a free, open-source database system for storing and scaling complex data workloads. It uses SQL and adds object-relational capabilities, with support for primitive and structured values as well as documents, geometric data, and custom types. Its supported formats include JSON/JSONB, XML, arrays, ranges, and UUIDs. For data integrity, it provides keys, constraints, locks, transactions, savepoints, and SQL-standard transaction isolation levels. Performance tools include multiple index types, query planning and optimization, parallel processing, partitioning, just-in-time expression compilation, and asynchronous I/O. Recovery and availability features include write-ahead logging, several replication methods, point-in-time recovery, and active standbys. Security options include multiple authentication methods, access controls, row- and column-level security, and multi-factor authentication. Extensions, procedural languages, and foreign data wrappers can connect PostgreSQL to other databases or streams. It runs on Linux, macOS, and Windows, and is self-hosted; no managed service is listed. The PostgreSQL License permits use, copying, modification, and distribution without a fee, subject to its conditions.