lmdb-zero

lmdb-zero is a near-zero-cost wrapper around LMDB designed to allow using the full range of features offered by LMDB while keeping it reasonably easy to write safe programs.

Documentation

Why another LMDB library?

There already exist the competing lmdb and lmdb-rs crates right now. Why write a third?

The main issue with the existing crates is that they try to abstract some properties of LMDB away, and as a result are not able to expose some of LMDB's functionality, and in some cases compromise safety.

lmdb-zero is instead as much as possible a 1:1 mapping of the raw API, mainly providing RAII constructs and integration into Rust's borrow checker to ensure safety.

Features

• Zero-copy API. Reads return references into the memory-mapped file. Using MDB_RESERVE to allocate space in the file and directly write to it is supported.

• Cursors directly map to the same operations provided by LMDB, but in a typesafe manner.

• Nested transactions.

• Full integration with the borrow checker. Read references are checked to not outlive their transaction or overlap with a write in the same transaction.

• Cursors and read transactions can be reset and reused.

Status

The API is complete but not necessarily completely stable; there may yet be unsound parts of the API or the implementations.

This crate has not been tested on architectures with strong alignment constraints. While the conversion API checks for correct alignment by default, issues such as #27060 could come up, and it is of course possible there are bugs in handling alignment here.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.