heed & heed3
[](#LICENSE)
[](https://crates.io/crates/heed)
[](https://docs.rs/heed)
[](https://deps.rs/repo/github/meilisearch/heed)
[](https://github.com/meilisearch/heed/actions/workflows/rust.yml)
A Rust-centric [LMDB](https://en.wikipedia.org/wiki/Lightning_Memory-Mapped_Database) abstraction with minimal overhead. This library enables the storage of various Rust types within LMDB, extending support to include Serde-compatible types. It not only supports the LMDB `mdb.master` branch but also the `mdb.master3` branch which features encryption-at-rest and checksumming.
## Simple Example Usage
Here is an example on how to store and read entries into LMDB in a safe and ACID way. For usage examples, see [examples/](examples/). To see more advanced usage techniques go check our [Cookbook](https://docs.rs/heed/latest/heed/cookbook/index.html).
```rust
use std::fs;
use std::path::Path;
use heed::{EnvOpenOptions, Database};
use heed::types::*;
fn main() -> Result<(), Box> {
let env = unsafe { EnvOpenOptions::new().open("my-first-db")? };
// We open the default unnamed database
let mut wtxn = env.write_txn()?;
let db: Database> = env.create_database(&mut wtxn, None)?;
// We open a write transaction
db.put(&mut wtxn, "seven", &7)?;
db.put(&mut wtxn, "zero", &0)?;
db.put(&mut wtxn, "five", &5)?;
db.put(&mut wtxn, "three", &3)?;
wtxn.commit()?;
// We open a read transaction to check if those values are now available
let mut rtxn = env.read_txn()?;
let ret = db.get(&rtxn, "zero")?;
assert_eq!(ret, Some(0));
let ret = db.get(&rtxn, "five")?;
assert_eq!(ret, Some(5));
Ok(())
}
```
## Working with two Crates: heed and heed3
The heed and heed3 crates manage a shared codebase. Within the heed3 folder, you can find the Cargo.toml specific to the heed3 crate.
To facilitate work on heed3, utilize the `convert-to-heed3.sh` script.
This script conveniently moves the `heed3/Cargo.toml` file to the `heed/` folder, updates the `heed::` references to `heed3::`, and generates a commit for easy rollback if needed.
## Building from Source
You can use this command to clone the repository:
```bash
git clone --recursive https://github.com/meilisearch/heed.git
cd heed
cargo build
```
However, if you already cloned it and forgot to initialize the submodules, execute the following command:
```bash
git submodule update --init
```