Overview and History

• Keith Bostic, co-architect of WiredTiger and a legendary figure in open-source operating systems, developed WiredTiger as part of MongoDB to enhance performance and scalability.
• WiredTiger is an embedded database engine designed to be a high-performing, scalable, low latency NoSQL key-value store with schema support.

Performance and Architecture

• General Purpose Toolkit: WiredTiger is versatile, aimed at solving general-purpose workloads.
• In-memory Performance: Utilizes techniques like Lock-Free algorithms (Hazard pointers) to avoid thread contention and enhance performance, especially on modern hardware.
• Skip Lists for Updates: Skip lists are used for updates to avoid locking and improve concurrent operations within pages.

Concurrency and Durability

• MVCC (MultiVersion Concurrency Control): Ensures data consistency by maintaining multiple versions of records in the cache.
• Durability without Journaling: WiredTiger can operate with or without journaling, facilitating high-performance single-node operations, particularly useful in scenarios where replication handles durability.

Compression and Storage Efficiency

• Implements various compression techniques (Snappy, lz4) and uses minimal space for indexing, significantly reducing storage requirements.
• Compression is pluggable and optional, enabling customization based on workload needs.
• Prefix Compression and Skip Lists: Used to minimize disk storage by storing and referencing only changes, not whole values.

Future Directions

• Focused on implementing encryption, refining advanced transactional semantics, and further improving performance checks like collective checkpointing.
• Continued integration and optimizations as a default storage engine within MongoDB.