FoundationDB

FoundationDB is an open-source, distributed, transactional key-value store renowned for providing full, multi-key ACID transactions across its entire distributed cluster. It achieves high performance, scalability, and fault tolerance by building upon a simple, ordered key-value core, which serves as a solid foundation for more complex data models. A key architectural feature is its use of "layers," which are client-side libraries that implement different data models (such as document, graph, or even relational) on top of the core transactional key-value API, making it a uniquely flexible and powerful platform for building a wide range of stateful applications that require strong consistency guarantees.

1. Introduction to FoundationDB
   1. What is FoundationDB
      1. Definition and Core Purpose
      2. Distributed Database Fundamentals
      3. Key-Value Store Architecture
   2. Historical Context
      1. Origins and Early Development
      2. Apple Acquisition
      3. Open Source Release
      4. Current Development Status
   3. Core Design Philosophy
      1. Simplicity at the Core
      2. Extensibility Through Layers
      3. Strong Consistency First
      4. Deterministic Behavior
   4. Fundamental Characteristics
      1. Distributed Architecture
      2. ACID Transactions Across Multiple Keys
      3. Horizontal Scalability
      4. High Performance and Low Latency
      5. Fault Tolerance
      6. Ordered Key-Value Model
   5. The Layers Concept
      1. Separation of Storage and Data Models
      2. Client-Side Data Model Implementation
      3. Flexibility for Custom Applications
      4. Layer Examples and Use Cases
   6. When to Use FoundationDB
      1. Strong Consistency Requirements
      2. Custom Stateful Services
      3. Database Foundation Layer
      4. Multi-Tenant Applications
      5. Scenarios to Avoid