kuguobing / xodus

Transactional schema-less embedded database used by JetBrains YouTrack and JetBrains Hub.

JetBrains Xodus is a transactional schema-less embedded database that is written in Java and Kotlin. It was initially developed for JetBrains YouTrack, an issue tracking and project management tool. Xodus is also used in JetBrains Hub, the user management platform for JetBrains' team tools, and in some internal JetBrains projects.

• Xodus is transactional and fully ACID-compliant.
• Xodus is highly concurrent. Reads are completely non-blocking due to MVCC and true snapshot isolation.
• Xodus is schema-less and agile. It does not require schema migrations or refactorings.
• Xodus is embedded. It does not require installation or administration.
• Xodus is written in pure Java and Kotlin.
• Xodus is free and licensed under Apache 2.0.

Hello Worlds!

To start using Xodus, define dependencies:

<!-- in Maven project -->
<dependency>
    <groupId>org.jetbrains.xodus</groupId>
    <artifactId>xodus-openAPI</artifactId>
    <version>1.3.232</version>
</dependency>

// in Gradle project
dependencies {
    compile 'org.jetbrains.xodus:xodus-openAPI:1.3.232'
}

Read more about managing dependencies.

There are three different ways to deal with data, which results in three different API layers: Environments, Entity Stores and Virtual File Systems.

Environments

Add dependency on org.jetbrains.xodus:xodus-environment:1.3.232.

try (Environment env = Environments.newInstance("/home/me/.myAppData")) {
    env.executeInTransaction(txn -> {
        final Store store = env.openStore("Messages", StoreConfig.WITHOUT_DUPLICATES, txn);
        store.put(txn, StringBinding.stringToEntry("Hello"), StringBinding.stringToEntry("World!"));
    });
}

Entity Stores

Add dependency on org.jetbrains.xodus:xodus-entity-store:1.3.232, org.jetbrains.xodus:xodus-environment:1.3.232 and org.jetbrains.xodus:xodus-vfs:1.3.232.

try (PersistentEntityStore entityStore = PersistentEntityStores.newInstance("/home/me/.myAppData")) {
    entityStore.executeInTransaction(txn -> {
        final Entity message = txn.newEntity("Message");
        message.setProperty("hello", "World!");
    });
}

Virtual File Systems

Add dependency on org.jetbrains.xodus:xodus-vfs:1.3.232 and org.jetbrains.xodus:xodus-environment:1.3.232.

try (Environment env = Environments.newInstance("/home/me/.myAppData")) {
    final VirtualFileSystem vfs = new VirtualFileSystem(env);
    env.executeInTransaction(txn -> {
        final File file = vfs.createFile(txn, "Messages");
        try (DataOutputStream output = new DataOutputStream(vfs.writeFile(txn, file))) {
            output.writeUTF("Hello ");
            output.writeUTF("World!");
        } catch (IOException e) {
            throw new ExodusException(e);
        }
    });
    vfs.shutdown();
}

Building from Source

Gradle is used to build, test, and publish. JDK 1.8 or higher is required. To build the project, run:

./gradlew build

To assemble JARs and skip running tests, run:

./gradlew assemble

Find out More

• Xodus wiki
• Report an issue
• Stack Overflow
• Xodus-DNQ: data definition and queries Kotlin DSL over Xodus
• EntityStore browser
• Check out the latest builds