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Installation

Datalevin can be installed with different methods, depending on how you plan to use it.

Clojure Library

The core of Datalevin is a Clojure library, simply add it to your project as a dependency and start using it!

If you use Leiningen build tool, add this to the :dependencies section of your project.clj file:

[datalevin "0.8.16"]

If you use Clojure CLI and deps.edn, declare the dependency like so:

{:deps {datalevin/datalevin {:mvn/version "0.8.16"}
        com.cognitect/transit-clj {:mvn/version "1.0.329"}}}

This library supports Java 8 and above.

Important: For JVM version newer than 11, you need to add the following JVM options:

--add-opens=java.base/java.nio=ALL-UNNAMED
--add-opens=java.base/sun.nio.ch=ALL-UNNAMED

Or you will get errors such as "Could not initialize class org.lmdbjava.ByteBufferProxy", and so on.

For lein, add a top level :jvm-opts in your project.clj like so:

:jvm-opts ["--add-opens=java.base/java.nio=ALL-UNNAMED"
           "--add-opens=java.base/sun.nio.ch=ALL-UNNAMED"]

For dep.edn, this is known to work:

:aliases {:jvm-base
           {:jvm-opts ["--add-opens=java.base/java.nio=ALL-UNNAMED"
                       "--add-opens=java.base/sun.nio.ch=ALL-UNNAMED"]}}

Then clj -A:jvm-base

Other JVM Languages

Datalevin can be used in other JVM languages than Clojure, such as Java, Scala, Kotlin, and so on, by using the official Clojure Java API. If you have done so, a PR to document your example will be welcome here. In addition, one can build a Datalevin wrapper in other JVM languages this way, and we will be happy to link to it here if you have done so.

GraalVM Native Image

If your application depends on the Datalevin library and you want to compile your application to a GraalVM native image, put org.clojars.huahaiy/datalevin-native instead (they have the same version number) in your project.clj or deps.edn file.

This is necessary because datelevin-native artifact contains GraalVM specific code that should not appear in a regular JVM library. See also this note.

Command Line Tool

A command line tool dtlv is built to work with Datalevin databases in shell scripting, doing work such as database backup/compaction, data import/export, query/transaction execution, server administration, and so on. The same binary can also run as a Datalevin server. This tool also includes a REPL with a Clojure interpreter, in addition to support all the database functions.

Unlike many other database software (e.g. SQLite, Postgres, etc.) that introduces a separate language for the command line, the same Clojure code works in both Datalevin library and Datalevin command line tool.

A native Datalevin is built by compiling into GraalVM native image. In addition to fast startup times, it should also have better index access speed, for the native image version does not incur JNI overhead and uses a comparator written in C, see blog post.

Here is how to get the Datalevin command line tool:

MacOS and Linux Package

Install using homebrew

brew install huahaiy/brew/datalevin

Windows Package

Install using scoop

# Note: if you get an error you might need to change the execution policy (i.e. enable Powershell) with
# Set-ExecutionPolicy RemoteSigned -scope CurrentUser
Invoke-Expression (New-Object System.Net.WebClient).DownloadString('https://get.scoop.sh')

scoop bucket add scoop-clojure https://github.com/littleli/scoop-clojure
scoop bucket add extras
scoop install datalevin

Docker

docker pull huahaiy/datalevin

See README on Docker hub for usage.

Direct Download

Or download the executable binary from github:

Unzip, put it on your path, and execute dtlv help:

  Datalevin (version: 0.8.16)

Usage: dtlv [options] [command] [arguments]

Commands:
  copy  Copy a database, regardless of whether it is now in use
  drop  Drop or clear a database
  dump  Dump the content of a database to standard output
  exec  Execute database transactions or queries
  help  Show help messages
  load  Load data from standard input into a database
  repl  Enter an interactive shell
  serv  Run as a server
  stat  Display statistics of database

Options:
  -a, --all                            Include all of the sub-databases
  -c, --compact                        Compact while copying
  -d, --dir PATH                       Path to the database directory
  -D, --delete                         Delete the sub-database, not just empty it
  -f, --file PATH                      Path to the specified file
  -g, --datalog                        Dump/load as a Datalog database
  -h, --help                           Show usage
  -l, --list                           List the names of sub-databases instead of the content
  -p, --port PORT  8898                Listening port number
  -r, --root ROOT  /var/lib/datalevin  Server root data directory
  -v, --verbose                        Show verbose server debug log
  -V, --version                        Show Datalevin version and exit

Type 'dtlv help <command>' to read about a specific command.

Starting dtlv without any arguments goes into the console:

  Datalevin (version: 0.8.16)

  Type (help) to see available functions. Some Clojure core functions are also available.
  Type (exit) to exit.

user> (help)

In addition to some Clojure core functions, the following functions are available:

In namespace datalevin.core

add                   add-doc               clear                 clear-dbi
close                 close-db              close-kv              closed-kv?
closed?               commit                conn-from-datoms      conn-from-db
conn?                 copy                  create-conn           datom
datom-a               datom-e               datom-v               datom?
datoms                db                    db?                   dir
doc-count             doc-indexed?          doc-refs              drop-dbi
empty-db              entid                 entity                entity-db
entries               get-conn              get-first             get-range
get-some              get-value             hexify-string         index-range
init-db               k                     list-dbis             listen!
new-search-engine     open-dbi              open-kv               opts
pull                  pull-many             put-buffer            q
range-count           range-filter          range-filter-count    read-buffer
remove-doc            reset-conn!           resolve-tempid        retract
rseek-datoms          schema                search                search-index-writer
seek-datoms           stat                  tempid                touch
transact              transact!             transact-async        transact-kv
unhexify-string       unlisten!             update-schema         v
visit                 with-conn             write

In namespace datalevin.interpret

definterfn            exec-code             inter-fn              inter-fn-from-reader
inter-fn?             load-edn

In namespace datalevin.client

assign-role           close-database        create-database       create-role
create-user           disconnect-client     drop-database         drop-role
drop-user             grant-permission      list-databases        list-databases-in-use
list-role-permissions list-roles            list-user-permissions list-user-roles
list-users            new-client            open-database         query-system
reset-password        revoke-permission     show-clients          withdraw-role

Can call function without namespace: (<function name> <arguments>)

Type (doc <function name>) to read documentation of the function

user>

You may want to launch dtlv in rlwrap to get a better REPL experience.

Uberjar

A JVM uberjar is downloadable to use as the command line tool. It is useful when one wants to run a Datalevin server and needs the efficiency of JVM's JIT, as GraalVM native image is AOT and not as efficient as JVM for long running programs, or when a pre-built native version is not available for your platform. For example, assuming your Java is newer than version 11:

java --add-opens=java.base/java.nio=ALL-UNNAMED --add-opens=java.base/sun.nio.ch=ALL-UNNAMED -jar datalevin-0.8.16-standalone.jar

This will start the Datalevin REPL.

java --add-opens=java.base/java.nio=ALL-UNNAMED --add-opens=java.base/sun.nio.ch=ALL-UNNAMED -jar datalevin-0.8.16-standalone.jar serv -r /tmp/test-server

Will run the Datalevin server on default port 8898, with root data path at /tmp/test-server.

Babashka Pod

The dtlv executable can also run as a Babashka pod. It is also possible to download Datalevin directly from pod registry within a Babashka script (not all versions are registered):

#!/usr/bin/env bb

(require '[babashka.pods :as pods])
(pods/load-pod 'huahaiy/datalevin "0.8.16")

For pod usage, an extra macro defpodfn is provided to define a custom function that can be used in a query, e.g.:

$ rlwrap bb
Babashka v0.8.16 REPL.
Use :repl/quit or :repl/exit to quit the REPL.
Clojure rocks, Bash reaches.

user=> (require '[babashka.pods :as pods])
nil
user=> (pods/load-pod "dtlv")
#:pod{:id "pod.huahaiy.datalevin"}
user=>  (require '[pod.huahaiy.datalevin :as d])
nil
user=> (d/defpodfn custom-fn [n] (str "hello " n))
#:pod.huahaiy.datalevin{:inter-fn custom-fn}
user=> (d/q '[:find ?greeting :where [(custom-fn "world") ?greeting]])
#{["hello world"]}
user=> (def conn (d/get-conn "/tmp/bb-test"))
#'user/conn
user=> (d/transact! conn [{:name "hello"}])
{:datoms-transacted 1}
user=> (d/q '[:find ?n :where [_ :name ?n]] (d/db conn))
#{["hello"]}
user=> (d/close conn)
nil
user=>

The example above uses dtlv binary in the PATH.

Command Line Tool❯

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