Lemmy v0.10.0 Release

Written by @dessalines and @nutomic, 2021-04-05


Since our last release in February, we’ve had ~150 commits to Lemmy. The biggest changes, as we’ll outline below, are a split of Lemmy’s user tables into federated and local tables, necessitating a v3 of Lemmy’s API, federated moderation, i18n support in join.lemmy.ml, and lots of back-end cleanup.

Lemmy Server


  • Rewrote config implementation, finally allowing us to use newer Rust versions.
  • Removed categories.
  • Various refactors.



  • It is now possible to add users from other instances as community mods.
  • Federating Matrix ID.
  • Many changes for better compatibility with ActivityPub standard.


  • Split the user_ into person and local_user tables.
  • Strictly typed commonly used ID columns, to prevent DB errors using i32 as ids.
  • Strictly typed URL fields, thanks to ajyoon.
  • Created default DB forms, now used in all the unit tests.

Lemmy UI

  • Now using utf-8 emojis.
  • Support for all the above changes to Lemmy.
  • Typescript-safe i18n strings, thanks to @shilangyu.
  • Added expandable post text (click on open book icon).
  • Prettier cross-posting, which does smart quoting.
  • Bugfixes for restoring scroll position on post page, custom site favicons, and autocomplete for login fields.

Lemmy Docs


  • Rewrote in inferno isomorphic, added i18n support via weblate.
  • Added a section on the support page thanking contributors.
  • Changed some page urls / titles

Upgrade notes

Important: there are multiple breaking changes:

  • Configuration via environment variables is not supported anymore, you must have all your config in the lemmy.hjson file ( except for LEMMY_CONFIG_LOCATION ).
  • The config format for allowed_instances and blocked_instances has changed, and you need to adjust your config file manually:
    • before: allowed_instances: ds9.lemmy.ml,enterprise.lemmy.ml
    • now: allowed_instances: ["ds9.lemmy.ml", "enterprise.lemmy.ml"] , and only one of the allowed_instances or blocked_instances blocks can be set.
  • The API has been upgraded from v2 to v3, so all clients need to be updated: lemmy-js-client: 0.9.9 -> 0.10.0 .

If you’d like to make a DB backup before upgrading, follow this guide.

To upgrade your instance to v0.10.0, simply follow the instructions in the documentation:

Compilation time

v0.9.0 (Rust 1.47) v0.10.0 (Rust 1.47) v0.10.0 (Rust 1.51)
Clean 140s 146s 119s
Incremental 28s 22s 19s

Despite ongoing efforts to speed up compilation, it has actually gotten slower when comparing with the same Rust version. Only thanks to improvements in newer Rust versions has our build process gotten faster. This could be simply because we added more code, while Lemmy v0.9.0 had 22.4k lines of Rust, v0.10.0 has 23.8k (an increase of 6%).

v0.9.0 build graph:

v0.10.0 build graph:

We extracted the crates lemmy_api_crud and lemmy_apub_receive from lemmy_api and lemmy_apub, respectively, and renamed lemmy_structs to lemmy_api_common. In the second graph you can see how parts of the api and apub crates are now built nicely in parallel, speeding up builds on multi-core systems.

On the other hand, some crates have gotten much slower to compile, in particular lemmy_db_queries (6.5s slower), lemmy_apub (6.5s slower if we include lemmy_apub_receive). And lemmy_db_views is quite slow, just as before.