LSM in a Week

Build a simple key-value storage engine in a week! And extend your LSM engine on the second + third week.

Book

The Mini-LSM book is available at https://skyzh.github.io/mini-lsm. You may follow this guide and implement the Mini-LSM storage engine. We have 3 weeks (parts) of the course, each of them consists of 7 days (chapters).

Community

You may join skyzh's Discord server and study with the mini-lsm community.

Add Your Solution

If you finished at least one full week of this course, you can add your solution to the community solution list at SOLUTIONS.md. You can submit a pull request and we might do a quick review of your code in return of your hard work.

Development

For Students

You should modify code in mini-lsm-starter directory.

cargo x install-tools
cargo x copy-test --week 1 --day 1
cargo x scheck
cargo run --bin mini-lsm-cli
cargo run --bin compaction-simulator

For Course Developers

You should modify mini-lsm and mini-lsm-mvcc

cargo x install-tools
cargo x check
cargo x book

If you changed public API in the reference solution, you might also need to synchronize it to the starter crate. To do this, use cargo x sync.

Code Structure

• mini-lsm: the final solution code for <= week 2
• mini-lsm-mvcc: the final solution code for week 3 MVCC
• mini-lsm-starter: the starter code
• mini-lsm-book: the course

We have another repo mini-lsm-solution-checkpoint at https://github.com/skyzh/mini-lsm-solution-checkpoint. In this repo, each commit corresponds to a chapter in the course. We will not update the solution checkpoint very often.

Demo

You can run the reference solution by yourself to gain an overview of the system before you start.

cargo run --bin mini-lsm-cli-ref
cargo run --bin mini-lsm-cli-mvcc-ref

And we have a compaction simulator to experiment with your compaction algorithm implementation,

cargo run --bin compaction-simulator-ref
cargo run --bin compaction-simulator-mvcc-ref

Course Structure

We have 3 weeks + 1 extra week (in progress) for this course.

• Week 1: Storage Format + Engine Skeleton
• Week 2: Compaction and Persistence
• Week 3: Multi-Version Concurrency Control
• The Extra Week / Rest of Your Life: Optimizations (unlikely to be available in 2025...)

Week + Chapter	Topic
1.1	Memtable
1.2	Merge Iterator
1.3	Block
1.4	Sorted String Table (SST)
1.5	Read Path
1.6	Write Path
1.7	SST Optimizations: Prefix Key Encoding + Bloom Filters
2.1	Compaction Implementation
2.2	Simple Compaction Strategy (Traditional Leveled Compaction)
2.3	Tiered Compaction Strategy (RocksDB Universal Compaction)
2.4	Leveled Compaction Strategy (RocksDB Leveled Compaction)
2.5	Manifest
2.6	Write-Ahead Log (WAL)
2.7	Batch Write and Checksums
3.1	Timestamp Key Encoding
3.2	Snapshot Read - Memtables and Timestamps
3.3	Snapshot Read - Transaction API
3.4	Watermark and Garbage Collection
3.5	Transactions and Optimistic Concurrency Control
3.6	Serializable Snapshot Isolation
3.7	Compaction Filters

Related Projects

mini-lsm inspired several projects used in production.

• SlateDB is an LSM engine over the object storage system.
• Tonbo stores parquet files directly on the object storage and organizes them in an LSM tree structure.

License

The Mini-LSM starter code and solution are under Apache 2.0 license. The author reserves the full copyright of the course materials (markdown files and figures).