ScyllaDB

ScyllaDB is a NoSQL database with a close-to-the-hardware, shared-nothing approach that optimizes raw performance, fully utilizes modern multi-core servers, and minimizes the overhead to DevOps. ScyllaDB is API-compatible with both Cassandra and DynamoDB, yet is much faster, more consistent, and with a lower TCO.

— ScyllaDB Homepage

ScyllaDB Setup and Connection

ScyllaDB is fully compatible with Cassandra. To use it as the data storage layer:

1. Spin up a Scylla cluster. You can do this using Scylla Cloud, using Docker, running Scylla in the cloud or on-prem. You can see a step-by-step guide on how to spin up a three node Scylla cluster using Docker in this lesson.
2. Run JanusGraph with “cql” as the storage.backend.
3. Specify the IP address of one of the Scylla nodes in your cluster as the storage.hostname.

Step by Step Tutorial

This Scylla University lesson provides step-by-step instructions for using JanusGraph with ScyllaDB as the data storage layer. The main steps in the lesson are:

• Spinning up a virtual machine
• Installing the prerequisites
• Running the JanusGraph server (using Docker)
• Running a Gremlin Console to connect to the new server (also in Docker)
• Spinning up a three-node Scylla Cluster and setting it as the data storage for the JanusGraph server
• Performing some basic graph operations

Usage of Scylla optimized driver

JanusGraph provides scylla storage.backend options in addition to generic cql option.
ScyllaDB can work using any of those storage options, but the dedicated scylla backend is better optimized for ScyllaDB. Thus, it's recommended to use scylla backend option with ScyllaDB whenever possible.
scylla storage option is included in janusgraph-scylla library but this library isn't shipped via janusgraph-all and this library is not part of the provided JanusGraph distributions.
To make scylla option available in JanusGraph it's necessary to replace org.janusgraph:janusgraph-cql with org.janusgraph:janusgraph-scylla if JanusGraph is used in Embedded Mode.

In case janusgraph-all dependency is used instead of explicit JanusGraph dependencies then the replacement to org.janusgraph:janusgraph-scylla can be done like below.

MavenGradle

<dependencies>
    <!-- Exclude `janusgraph-cql` from `janusgraph-all` -->
    <dependency>
        <groupId>org.janusgraph</groupId>
        <artifactId>janusgraph-all</artifactId>
        <version>1.0.0</version>
        <exclusions>
            <exclusion>
                <groupId>org.janusgraph</groupId>
                <artifactId>janusgraph-cql</artifactId>
            </exclusion>
        </exclusions>
    </dependency>

    <!-- Include `janusgraph-scylla` -->
    <dependency>
        <groupId>org.janusgraph</groupId>
        <artifactId>janusgraph-scylla</artifactId>
        <version>1.0.0</version>
    </dependency>
</dependencies>

/* Exclude `janusgraph-cql` from `janusgraph-all` */
compile("org.janusgraph:janusgraph-all:1.0.0") {
    exclude group: 'org.janusgraph', module: 'janusgraph-cql'
}
/* Include `janusgraph-scylla` */
compile "org.janusgraph:janusgraph-scylla:1.0.0"

Using Scylla driver in JanusGraph Server provided via the standard distribution builds

Note

The manual process described below is temporary and should be replaced by automated process after the issue janusgraph/janusgraph#3580 is resolved.

In case scylla storage option is needed to be used in JanusGraph distribution then it's necessary to replace the next DataStax provided CQL driver with Scylla provided CQL driver. The default JanusGraph distribution builds contain only DataStax drivers, but not Scylla drivers because they are conflicting. However, it's possible to build the same distribution build but with Scylla drivers enabled instead. To do this, you can use the following command inside the JanusGraph repository:

Bash

mvn clean install -Pjanusgraph-release -Puse-scylla -DskipTests=true --batch-mode --also-make -Dgpg.skip=true

This command will generate distribution builds (both normal and full distribution build) in the following directory: janusgraph-dist/target/.

Otherwise, if you can't build distribution on your own, you can use the JanusGraph provided distribution and replace the following libraries in lib directory (all libraries can be downloaded via Maven Central Repository). - org.janusgraph:janusgraph-cql with org.janusgraph:janusgraph-scylla - org.janusgraph:cassandra-hadoop-util with org.janusgraph:scylla-hadoop-util - com.datastax.oss:java-driver-core with com.scylladb:java-driver-core - com.datastax.oss:java-driver-query-builder with com.scylladb:java-driver-query-builder - com.datastax.cassandra:cassandra-driver-core with com.scylladb:scylla-driver-core

The versions of com.scylladb:java-driver-core and com.scylladb:java-driver-query-builder should be equal to the version found in pom.xml of org.janusgraph:janusgraph-scylla. The version of com.scylladb:scylla-driver-core should be equal to the version found in org.janusgraph:scylla-hadoop-util.

After replacement is done it will be possible to use scylla as storage.backend options which will use the optimized Scylla driver.