« BackUp to date Rust bindings for LMDBcrates.ioSubmitted by seanwatters 4 days ago
  • Pesthuf 22 minutes ago

    What kinds of use cases do you all use LMDB or other key-value stores for? I can somehow never really find a good one. Almost all databases, no matter how trivial, will sooner rather than later need more features so I always reach for SQLite instead.

    Still, I'd really like to make use of it. But for what? Caching?

    • seanwatters 4 days ago

      not sure why all the existing crates have gone so far out of date. i feel like generating bindings isn't that hard if you've done it before but can be a blocker for people who haven't so maybe this will help.

      some of the existing crates had the -sys suffix but it didn't seem like they were actually checking for it on the system (i'm not sure that LMDB is installed by default on most systems anyway?) so opted to not use it.

      chose to keep the version in step with LMDB (current looks like 0.9.70 in the lmdb.h).

      will regenerate anytime i become aware of a version bump for LMDB.

      • jnwatson an hour ago

        LMDB Python maintainer here. 0.9.70 is not really the latest release. It isn't binary compatible with official "releases" though it has sneaked out in a few bindings.

        Latest is 0.9.31.

        • Shawnecy 4 days ago

          > not sure why all the existing crates have gone so far out of date.

          Pure speculation on my part: maybe people are choosing Rust-based embedded key value stores like sled or redb?

          • sbt567 4 days ago
            • jszymborski 2 hours ago

              Only slightly off topic, but any of these support fast concurrent writes? LMDB really slows down for me when I'm trying to write a lot to it and locking means i cant use concurrency to speed it up.

          • mmastrac 2 hours ago

            For those of us who don't know, LMDB is a DB, somewhat akin to sqlite or Berkeley DB. It took a bit of time to find the info by chasing links.

            Please add READMEs to your projects with appropriate links, folks.

            https://crates.io/crates/liblmdb <-- says it is bindings for LMDB

            ... which links to the repo

            https://github.com/ordinarylabs/liblmdb

            Which has a link to the LMDB repo here (just a submodule) ...

            https://github.com/LMDB/lmdb/tree/9c9d34558cc438f99aebd1ab58...

            Which has no info about the project, but links to

            https://www.openldap.org/software/repo.html

            Which also has no info about the project, but has an LMDB link which leads to

            https://www.symas.com/lmdb

            Which finally explains:

            > Symas LMDB is an extraordinarily fast, memory-efficient database we developed for the OpenLDAP Project. With memory-mapped files, LMDB has the read performance of a pure in-memory database while retaining the persistence of standard disk-based databases.

            > Bottom line, with only 32KB of object code, LMDB may seem tiny. But it’s the right 32KB. Compact and efficient are two sides of a coin; that’s part of what makes LMDB so powerful.

            There's also a wikipage:

            https://en.wikipedia.org/wiki/Lightning_Memory-Mapped_Databa...