heed

A fully typed LMDB/MDBX wrapper with minimum overhead, uses bytemuck internally.

This library is able to serialize all kind of types, not just bytes slices, even Serde types are supported.

Using MDBX instead of LMDB

Heed can also be used with MDBX, this is a compatible backend, you can activate it by using the mdbx feature. When MDBX is used the generated databases cannot be read by using the lmdb feature, those two kv-stores are not compatible and vice-versa.

Notice that some specific features will only be accessible by using the mdbx cargo feature. Environment creation flags depends on the backend you chose.

To test that heed works with MDBX you can run this command:

cargo test --features 'mdbx serde-json' --no-default-features

Example Usage

fs::create_dir_all("target/heed.mdb")?;
let env = EnvOpenOptions::new().open("target/heed.mdb")?;

// We open the default unamed database.
// Specifying the type of the newly created database.
// Here we specify that the key is an str and the value a simple integer.
let db: Database<Str, OwnedType<i32>> = env.create_database(None)?;

// We then open a write transaction and start writing into the database.
// All of those puts are type checked at compile time,
// therefore you cannot write an integer instead of a string.
let mut wtxn = env.write_txn()?;
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 available.
// When we read we also type check at compile time.
let 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));

You want to see more about all the possibilities? Go check out the examples.