Section 1.1: How Graph Databases Function

Utilizing graph theory and property graph concepts, graph databases store data in a structure that prioritizes relationships. Unlike traditional databases that organize data in tables, graph databases utilize vertices for data entities and edges for their relationships.

The advantages of graph databases include:

• Emphasis on maintaining relationships between data points.
• Consistent performance regardless of the volume of data.
• Flexible schemas that allow for structural adjustments without compromising existing data.
• An agile approach that adapts easily to application changes.

Section 1.2: Graph vs. Relational Databases

When comparing graph databases to relational databases, several key distinctions emerge:

• Relational databases are structured in tables (rows and columns), whereas graph databases use vertices and edges.
• Relationships in relational databases are established through foreign keys, while graph databases rely on edges.
• Graph databases eliminate the need for complex join operations, simplifying data retrieval.
• Use cases for relational databases often focus on transactions, while graph databases emphasize relationship-heavy scenarios.

Both types of databases serve the purpose of data storage, but their applications vary based on specific needs.

Installing NebulaGraph

Installing NebulaGraph on a local or cloud environment can be achieved through several methods outlined in its documentation. To set up NebulaGraph, ensure you are using a Linux or Ubuntu system.

The simplest installation route involves following the quick start guide to use the RPM or DEB package system. For my setup, I utilized Ubuntu 18.04.

Begin by downloading the necessary package using the following commands:

After downloading the DEB package, proceed with the installation:

sudo dpkg -i nebula-graph-3.2.1.ubuntu1804.amd64.deb

To start the NebulaGraph database, execute the following command:

sudo /usr/local/nebula/scripts/nebula.service

Next, you will need to install the Nebula console to run various commands. Obtain the release for Linux as follows:

Remember to change the permission to execute the console:

chmod 111 nebula-console

Utilizing the console can be initiated with the following command:

./nebula-console -addr 127.0.0.1 -port 9669 -u root -p root

For first-time users, you must add storage hosts:

ADD HOSTS 127.0.0.1:9669

If all steps are executed correctly, you will be ready to explore NebulaGraph. For visualization, consider using Nebula Studio with a sample dataset.

The second video, "The Open-Source Distributed Graph Database: Nebula Graph - Wey Gu - vesoft," provides further insights into the capabilities and features of NebulaGraph.

Exploring NebulaGraph

NebulaGraph employs a specialized query language known as nGQL (NebulaGraph Query Language), which resembles SQL and is tailored for graph pattern queries. If you are familiar with SQL, transitioning to nGQL will be straightforward.

For instance, to create a space in NebulaGraph, the following command is used:

CREATE SPACE basketballplayer(partition_num=15, replica_factor=1, vid_type=fixed_string(30));

To insert a vertex, you would use:

INSERT VERTEX player(name, age) VALUES "player100":("Tim Duncan", 42);

Adding an edge can be accomplished with:

INSERT EDGE follow(degree) VALUES "player101" -> "player100":(95);

Lastly, to read data, you can execute a GO query:

GO FROM "player101" OVER follow WHERE properties($$).age >= 35 YIELD properties($$).name AS Teammate, properties($$).age AS Age;

If you wish to experiment with NebulaGraph without any installations, you can access it through the online NebulaGraph Studio.