# LSM in a Week

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

## [Tutorial](https://skyzh.github.io/mini-lsm)

The Mini-LSM book is available at [https://skyzh.github.io/mini-lsm](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 tutorial, each of them consists of 7 days (chapters).

## Community

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

[![Join skyzh's Discord Server](https://dcbadge.vercel.app/api/server/ZgXzxpua3H)](https://skyzh.dev/join/discord)

**Add Your Solution**

If you finished at least one full week of this tutorial, you can add your solution to the community solution list at [SOLUTIONS.md](./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 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`.

## 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 tutorial

We have another repo mini-lsm-solution-checkpoint at [https://github.com/skyzh/mini-lsm-solution-checkpoint](https://github.com/skyzh/mini-lsm-solution-checkpoint). In this repo, each commit corresponds to a chapter in the tutorial. 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
```

## Progress

We are working on chapter 3 and more test cases for all existing contents.

* 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 2024...)

✅: Finished \
🚧: WIP and will likely be available soon

| Week + Chapter | Topic                                           | Solution | Starter Code | Writeup |
| -------------- | ----------------------------------------------- | -------- | ------------ | ------- |
| 3.1            | Timestamp Key Encoding                          | ✅        | ✅            | ✅       |
| 3.2            | Snapshot Read - Blocks, Memtables, and SSTs     | ✅        | ✅            | ✅       |
| 3.3            | Snapshot Read - Engine Read Path                | ✅        | ✅            | ✅       |
| 3.4            | Watermark and Garbage Collection                | ✅        | ✅            | ✅       |
| 3.5            | Transactions and Optimistic Concurrency Control | ✅        | ✅            | ✅       |
| 3.6            | Serializable Snapshot Isolation                 | ✅        | ✅            | ✅       |
| 3.7            | Compaction Filter                               | 🚧        |              |         |

## License

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