memgraph/docs/user_technical/quick-start.md

Quick Start

This chapter outlines installing and running Memgraph, as well as executing basic queries against the database.

Installation

The Memgraph binary is offered as:

• Debian package for Debian 9 (Stretch);
• RPM package for CentOS 7 and
• Docker image.

After downloading the binary, proceed to the corresponding section below.

NOTE: Currently, newer versions of Memgraph are not backward compatible with older versions. This is mainly noticeable by unsupported loading of storage snapshots between different versions.

Docker Installation

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

After installing and running Docker, download the Memgraph Docker image and import it with the following command.

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

Memgraph is then started with another docker command.

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

On success, expect to see output similar to the following.

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

Memgraph is now ready to process queries, you may now proceed to querying. To stop Memgraph, press Ctrl-c.

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.

Debian Package Installation

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

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

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

systemctl start memgraph

To verify that Memgraph is running, run the following command.

journalctl --unit memgraph

It is expected to see something like the following output.

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

Memgraph is now ready to process queries, you may now proceed to querying. To shutdown Memgraph server, issue the following command.

systemctl stop memgraph

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

RPM Package Installation

If you downloaded the RPM package of Memgraph, you can install it by running the following command.

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

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

systemctl start memgraph

To verify that Memgraph is running, run the following command.

journalctl --unit memgraph

It is expected to see something like the following output.

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

Memgraph is now ready to process queries, you may now proceed to querying. To shutdown Memgraph server, issue the following command.

systemctl stop memgraph

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

Querying

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

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

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

neo4j-client --insecure -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' (insecure)
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;

Where to Next

To learn more about the openCypher language, visit openCypher Query Language chapter in this document. For real-world examples of how to use Memgraph visit Examples chapter. If you wish to use a programming language to execute queries on Memgraph, go to the Drivers chapter. Details on what can be stored in Memgraph are in Data Storage chapter.

We welcome and encourage your feedback!