juxt / crux

Crux is a general purpose database with graph-oriented bitemporal indexes. Datalog, SQL & EQL queries are supported, and Java, HTTP & Clojure APIs are provided.

Crux follows an unbundled architectural approach, which means that it is assembled from decoupled components through the use of an immutable log and document store at the core of its design. A range of storage options are available for embedded usage and cloud native scaling.

Bitemporal indexing of schemaless documents enables broad possibilities for creating layered extensions on top, such as to add additional transaction, query, and schema capabilities. In addition to SQL, Crux supplies a Datalog query interface that can be used to express complex joins and recursive graph traversals.

Quick Links

• Documentation

• Maven releases - Clojars

  <dependency>
    <groupId>juxt</groupId>
    <artifactId>crux-core</artifactId>
    <version>20.09-1.12.1-beta</version>
  </dependency>

  [juxt/crux-core "20.09-1.12.1-beta"]

  juxt/crux-core {:mvn/version "20.09-1.12.1-beta"}

• Release notes

• Support: Zulip community chat | GitHub Discussions | crux@juxt.pro

• Development:

  • Kanban board
  • CircleCI build:

Unbundled Architecture

Crux embraces the transaction log as the central point of coordination when running as a distributed system. Use of a separate document store enables simple eviction of active and historical data to assist with technical compliance for information privacy regulations.

What do we have to gain from turning the database inside out? Simpler code, better scalability, better robustness, lower latency, and more flexibility for doing interesting things with data.

— Martin Kleppmann

This design makes it feasible and desirable to embed Crux nodes directly within your application processes, which reduces deployment complexity and eliminates round-trip overheads when running complex application queries.

Repo Layout

Crux is split across multiple projects which are maintained within this repository. crux-core contains the main functional components of Crux along with interfaces for the pluggable storage components (Kafka, LMDB, RocksDB etc.). Implementations of these storage options are located in their own projects.

Project directories are published to Clojars independently so that you can maintain granular dependencies on precisely the individual components needed for your application.

Developing inside this Crux project

The top-level project ties all the other projects together for convenience whilst working within this repo.

• To run a Clojure REPL that includes dependencies for all components of Crux, first build the sub-modules using lein sub install.
• Start a REPL with lein repl (with --headless if you're just going to connect to it from your editor).
• Once you've connected to the REPL, in the user namespace, run:
  • (dev) to require and go to the dev namespace.
  • (go) to start up the dev node
  • (halt!) to stop it
  • (reset) to stop it, reload changed namespaces, and restart it
  • (reset-all) to stop it, reload all namespaces, and restart it
  • if you're using Emacs/CIDER, cider-ns-refresh will do all this for you - C-c M-n M-r, , s x in Spacemacs
  • Conjure users can use ConjureRefresh, see the docs for bindings
  • see Integrant REPL for more details.
• You should now have a running Crux node under (dev/crux-node) - you can verify this by calling (crux/status (crux-node)) (in the dev namespace).
• Most of the time, you shouldn't need to bounce the REPL, but:
  • if you add a module, or change any of the dependencies of any of the modules, that'll require another lein sub install and a REPL bounce
  • if you change any of the Java classes, that'll require a lein sub javac and a REPL bounce
  • otherwise, (dev/reset) (or just (reset) if you're already in the dev ns) should be sufficient.
• You can run module tests from the root of the git repo without a lein sub install, because of the lein checkouts - all of the tests are in scope here, so things like lein test :only crux.tx-test should also work.
• Please don't put any more side-effecting top-level code in dev namespaces - you'll break this reload ability and make me sad.

Testing

The recommended way of running the full test suite is lein build.

The test suite relies on the timeout command line utility, this comes as a default on Linux but isn't preinstalled on MacOS. You can get it with brew install coreutils && echo 'alias timeout=gtimeout' >> ~/.bashrc'

Copyright & License

The MIT License (MIT)

Copyright © 2018-2020 JUXT LTD.

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Dependencies

A complete list of compiled dependencies and corresponding licenses is maintained and available on request.