lmdb-zig

LMDB using the Zig build system. Includes Ziggified bindings.

Versions

The latest branch tracks the latest release in the upstream LMDB repo.
We use tags named zA.B.C, corresponding to the upstream version numbers.

Usage

Add to your build.zig.zon by running zig fetch --save=lmdb https://github.com/nolanderc/lmdb-zig#z0.9.31.

You can then add it to your imports in build.zig:

const lmdb = b.dependency("lmdb", .{
    .target = target,
    .optimize = .ReleaseSafe,
});
exe.root_module.addImport("", lmdb.module("lmdb"));

Using the Bindings

Your entrypoint is the Environment, most easily used through its init method.
From here you can start a transaction with Environment.beginTransaction.
With this transaction you can open a database with Transaction.openDatabase.
With the database open, you can use either Transaction.get or Transaction.put.
(Optional) For advanced usage you can create a Cursor by calling Transaction.openCursor.

Using the C API

The full original C API is accessed through @import("lmdb").c.

Example

const std = @import("std");
const lmdb = @import("lmdb");

pub fn main() !void {
    const db_path = "/tmp/example-db";

    try std.fs.cwd().makePath(db_path);

    const env = try lmdb.Environment.init(.{
        .map_size = 1 << 32,
        .max_databases = 2,
        .open = .{ .path = db_path },
    });
    defer env.close();

    {
        var txn = try env.beginTransaction(.{});
        defer txn.abort();

        const db = try txn.openDatabase(.{ .name = "people", .flags = .{ .create = true } });
        defer db.close(env);
        try txn.clearDatabase(db);

        // prints 'null':
        std.debug.print("value: {?s}\n", .{try txn.get(db, "James T. Kirk")});
        std.debug.print("value: {?s}\n", .{try txn.get(db, "Jean-Luc Picard")});
        std.debug.print("value: {?s}\n", .{try txn.get(db, "Luke Skywalker")});
        std.debug.print("value: {?s}\n", .{try txn.get(db, "Darth Vader")});

        // insert values into the database:
        try txn.put(db, "James T. Kirk", "Star Trek");
        try txn.put(db, "Luke Skywalker", "Star Wars");

        // conditionally insert
        if (try txn.getOrPut(db, "Luke Skywalker", "Star Wars IV")) |previous| {
            std.debug.print("found existing: {s}\n", .{previous});
        }

        // reserve space before inserting:
        const reserved = try txn.reserve(db, "Jean-Luc Picard", 9);
        @memcpy(reserved, "Star Trek");

        // read back the inserted values:
        std.debug.print("value: {?s}\n", .{try txn.get(db, "James T. Kirk")});
        std.debug.print("value: {?s}\n", .{try txn.get(db, "Jean-Luc Picard")});
        std.debug.print("value: {?s}\n", .{try txn.get(db, "Luke Skywalker")});
        std.debug.print("value: {?s}\n", .{try txn.get(db, "Darth Vader")});

        // commit the changes to the database
        try txn.commit();
    }
}