CockroachDB

Amazon RDS is a hosted PostgreSQL database service from Amazon Web Services (AWS). In the cited architecture, it was used as the database for version one of a payments platform.

PostgreSQL is an open-source relational database management system maintained by the PostgreSQL Global Development Group. It provides SQL-compliant, ACID transactions, MVCC concurrency, and extensibility through custom types, functions and extensions, and is used for general-purpose and enterprise database workloads.

Supabase is a hosted Postgres development platform for building production web, mobile, and AI applications, built from open-source components and available for self-hosting or local development. It provides a managed Postgres database, authentication and authorization, Row Level Security, auto-generated REST and GraphQL APIs, realtime database-change subscriptions over WebSockets, Edge Functions and serverless database functions, file storage, and an AI vector and embeddings toolkit. Its architecture combines PostgreSQL with services including PostgREST for REST APIs, GoTrue for JWT-based authentication and session management, Realtime for converting PostgreSQL replication changes to JSON broadcasts, Storage for S3-compatible file management with Postgres permissions, and pg_graphql for GraphQL access. It also provides dashboard tools such as table and SQL editors, policy management, deployment workflows, and official client libraries for JavaScript, Flutter, Swift, and Python, with additional community libraries for other languages.

DuckDB is an in-process SQL OLAP database management system for analytical workloads. It uses a PostgreSQL-inspired SQL dialect, can run from edge devices to servers, and reads and writes formats including CSV, JSON, Parquet, Iceberg, and Vortex both locally and in object storage. Extensions add functions and format support, while native clients provide APIs for Python, Go, Java, Node.js, C, C++, R, Rust, and ODBC. DuckDB is open source and MIT-licensed, with governance by the independent DuckDB Foundation.

ClickHouse is an open-source, column-oriented database management system for online analytical processing (OLAP) and real-time analytics. It stores data by column and uses optimized compression and vectorized query execution to process analytical SQL queries while using available CPU resources efficiently. It supports large-scale workloads such as real-time analytics, observability, data warehousing, and machine learning or generative AI applications, including vector search and aggregations. ClickHouse can be self-managed on a machine or deployed through ClickHouse Cloud on AWS, Google Cloud, and Microsoft Azure. ClickHouse Local runs queries on local files such as CSV, TSV, and Parquet without a server. The project provides installers for macOS, Linux, FreeBSD, and Windows, as well as Docker and playground options; the self-managed database is open source.