memgraph/docs/user_technical/tutorial__quick_start.md

Quick Start

This article briefly outlines the basic steps necessary to install and run Memgraph. It also gives a brief glimpse into the world of OpenCypher and outlines some information on programmatic querying of Memgraph. The users should also make sure to read and fully understand the implications of telemetry at the very end of the article.

Installation

With regards to their own preference, users can download the Memgraph binary as:

• a Debian package for Debian 9 (Stretch)
• a RPM package for CentOS 7
• a Docker image

After downloading the binary, users are advised to proceed to the corresponding section below which outlines the installation details.

It is important to note that newer versions of Memgraph are currently not backward compatible with older versions. This is mainly noticeable by being unable to load storage snapshots between different versions.

Debian Package Installation

After downloading Memgraph as a Debian package, install it by running the following:

dpkg -i /path/to/memgraph_<version>.deb

On successful installation, Memgraph should already be running. To make sure that is true, user can start it explicitly with the command:

systemctl start memgraph

To verify that Memgraph is running, user can run the following command:

journalctl --unit memgraph

If successful, the user should receive an output similar to the following:

Nov 23 13:40:13 hostname memgraph[14654]: Starting 8 BoltS workers
Nov 23 13:40:13 hostname memgraph[14654]: BoltS server is fully armed and operational
Nov 23 13:40:13 hostname memgraph[14654]: BoltS listening on 0.0.0.0 at 7687

At this point, Memgraph is ready to process queries. To try out some elementary queries, the user should proceed to querying section of this article.

To shut down the Memgraph server, issue the following command:

systemctl stop memgraph

Memgraph configuration is available in /etc/memgraph/memgraph.conf. If the configuration is altered, Memgraph needs to be restarted.

RPM Package Installation

After downloading the RPM package of Memgraph, the user can install it by issuing the following command:

rpm -U /path/to/memgraph-<version>.rpm

After the successful installation, Memgraph can be started as a service. To do so, the user can type the following command:

systemctl start memgraph

To verify that Memgraph is running, the user should run the following command:

journalctl --unit memgraph

If successful, the user should receive an output similar to the following:

Nov 23 13:40:13 hostname memgraph[14654]: Starting 8 BoltS workers
Nov 23 13:40:13 hostname memgraph[14654]: BoltS server is fully armed and operational
Nov 23 13:40:13 hostname memgraph[14654]: BoltS listening on 0.0.0.0 at 7687

At this point, Memgraph is ready to process queries. To try out some elementary queries, the user should proceed to querying section of this article.

To shut down the Memgraph server, issue the following command:

systemctl stop memgraph

Memgraph configuration is available in /etc/memgraph/memgraph.conf. If the configuration is altered, Memgraph needs to be restarted.

Docker Installation

Before proceeding with the installation, the user should install the Docker engine on their system. Instructions on how to install Docker can be found on the official Docker website. Memgraph's Docker image was built with Docker version 1.12 and should be compatible with all newer versions.

After successful Docker installation, the user should install the Memgraph Docker image and import it using the following command:

docker load -i /path/to/memgraph-<version>-docker.tar.gz

To actually start Memgraph, the user should issue the following command:

docker run -p 7687:7687 \
  -v mg_lib:/var/lib/memgraph -v mg_log:/var/log/memgraph -v mg_etc:/etc/memgraph \
  memgraph

If successful, the user should be greeted with the following message:

Starting 8 workers
Server is fully armed and operational
Listening on 0.0.0.0 at 7687

At this point, Memgraph is ready to process queries. To try out some elementary queries, the user should proceed to querying section of this article.

To stop Memgraph, press Ctrl-c.

Note about named volumes

Memgraph configuration is available in Docker's named volume mg_etc. On Linux systems it should be in /var/lib/docker/volumes/mg_etc/_data/memgraph.conf. After changing the configuration, Memgraph needs to be restarted.

If it happens that the named volumes are reused between different Memgraph versions, Docker will overwrite a folder within the container with existing data from the host machine. If a new file is introduced, or two versions of Memgraph are not compatible, some features might not work or Memgraph might not be able to work correctly. We strongly advise the users to use another named volume for a different Memgraph version or to remove the existing volume from the host with the following command:

docker volume rm <volume_name>

Note for OS X/macOS Users

Although unlikely, some OS X/macOS users might experience minor difficulties after following the Docker installation instructions. Instead of running on localhost, a Docker container for Memgraph might be running on a custom IP address. Fortunately, that IP address can be found using the following algorithm:

1. Find out the container ID of the Memgraph container

By issuing the command docker ps the user should get an output similar to the following:

CONTAINER ID        IMAGE               COMMAND                  CREATED        ...
9397623cd87e        memgraph            "/usr/lib/memgraph/m…"   2 seconds ago  ...

At this point, it is important to remember the container ID of the Memgraph image. In our case, that is 9397623cd87e.

2. Use the container ID to retrieve an IP of the container

docker inspect -f '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' 9397623cd87e

The command above should yield the sought IP. If that IP does not correspond to localhost, it should be used instead of localhost when firing up the neo4j-client in the querying section.

Querying

Memgraph supports the openCypher query language which has been developed by Neo4j. It is a declarative language developed specifically for interaction with graph databases which is currently going through a vendor-independent standardization process.

The easiest way to execute openCypher queries against Memgraph is by using Neo4j's command-line tool. The command-line neo4j-client can be installed as described on the official website.

After installing neo4j-client, the user can connect to the running Memgraph instance by issuing the following shell command:

neo4j-client -u "" -p ""  localhost 7687

After the client has started it should present a command prompt similar to:

neo4j-client 2.1.3
Enter `:help` for usage hints.
Connected to 'neo4j://@localhost:7687'
neo4j>

At this point it is possible to execute openCypher queries on Memgraph. Each query needs to end with the ; (semicolon) character. For example:

CREATE (u:User {name: "Alice"})-[:Likes]->(m:Software {name: "Memgraph"});

The above will create 2 nodes in the database, one labeled "User" with name "Alice" and the other labeled "Software" with name "Memgraph". It will also create a relationship that "Alice" likes "Memgraph".

To find created nodes and relationships, execute the following query:

MATCH (u:User)-[r]->(x) RETURN u, r, x;

Supported Languages

If users wish to query Memgraph programmatically, they can do so using the Bolt protocol. Bolt was designed for efficient communication with graph databases and Memgraph supports Version 1 of the protocol. Bolt protocol drivers for some popular programming languages are listed below:

• Java
• Python
• JavaScript
• C#
• Ruby
• Haskell
• PHP

We have included some basic usage examples for some of the supported languages in the article about programmatic querying.

Telemetry

Telemetry is an automated process by which some useful data is collected at a remote point. At Memgraph, we use telemetry for the sole purpose of improving our product, thereby collecting some data about the machine that executes the database (CPU, memory, OS and kernel information) as well as some data about the database runtime (CPU usage, memory usage, vertices and edges count).

Here at Memgraph, we deeply care about the privacy of our users and do not collect any sensitive information. If users wish to disable Memgraph's telemetry features, they can easily do so by either altering the line in /etc/memgraph/memgraph.conf that enables telemetry (--telemetry-enabled=true) into --telemetry-enabled=false, or by including the --telemetry-enabled=false as a command-line argument when running the executable.

Where to Next

To learn more about the openCypher language, the user should visit our openCypher Query Language article. For real-world examples of how to use Memgraph, we strongly suggest reading through the following articles:

• Analyzing TED Talks
• Graphing the Premier League
• Exploring the European Road Network

Details on what can be stored in Memgraph can be found in the article about Data Storage.

We welcome and encourage your feedback!