Another Swift LMDB Wrapper

craigwrong · November 3, 2026, 8:28pm

Hello, fellow Swifters…

I'm here to share a little side project that I created with the help of a robot… myself supervising along the way

Yes, it's another LMDB wrapper but this one has some niceties like:

C library fully annotated with LLVM API Notes for safe interoperability wrappers
Thin wrapper using spans / RawSpan and 0-copy semantics
Strict memory safety checked
~Copyable ~Escapable DB transaction API with optional closure based read/writes
Support for binary parsable and encodable key/values
Exhaustive tests including exit tests and compilation failure tests for ~Escapable flows
DocC documented with additional articles

We are currently testing it within the Swift Bitcoin project with pretty encouraging results both performance and readability-wise.

As always any feedback is both welcome and appreciated.

Keep on Swifting

README-Swift.md

main

# LMDB for Swift — Safe Interop Layer

A fork of [swiftlang/swift-lmdb](https://github.com/swiftlang/swift-lmdb) that adds a
minimal, memory-safe Swift API on top of LMDB, driven by hand-written
[API notes](https://clang.llvm.org/docs/APINotes.html) and Swift's `SafeInteropWrappers`.

Everything new lives in `swift-*` folders at the root, so merging from upstream only ever
conflicts in `Package.swift`:

```
swift-include/module.modulemap          CLMDBInterop: a second view of lmdb.h
swift-include/CLMDBInterop.apinotes     hand-written annotations for that view
swift-src/LMDB/                         the Swift wrapper (module LMDB)
swift-src/LMDB/LMDB.docc/               DocC documentation catalog and articles
swift-test/LMDBTests/                   Swift Testing suite
swift-test/CompileFailures/             code that must NOT compile
swift-test/check-compile-failures.sh    checks that it doesn't
```

`libraries/liblmdb/` and `Sources/CLMDB/` are untouched, and the `CLMDB` module imports

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