Neo4j interview questions and Answers

It’s an open source, graph database management system used to find the exact relations between data and then extract their true value accordingly. This service is implemented in Java. Due to its excellent performance, responsiveness, flexibility, and scalability; today Neo4j is one of the most business preferred graph database management system in the world.

Neo4j has tons of features for developers. Here are a few best of them:

• It follows a flexible schema and data model called graph model.
• It supports full ACID properties.
• Users can scale the database by increasing the number of reads/writes and volume, without affecting the speed of the query processing and data integrity.
• High end data safety and reliability.
• Built-in Neo4j browser web applications to create and retrieve graph data

Neo4j 3.5.3 is the latest version of this graph database management system which was released on 11 February 2019. It came with various significant feature improvements and bug fixes for the developers.

Neo4j uses Cypher as its query language. It’s a declarative graph query language that allows developers for efficient and expressive querying and updating various properties of a graph. It’s a simple yet compelling language.

In Neo4j, Node is a record or data present in a graph database. Here the CREATE statement is used by the developers to create a Node. Users can use the CREATE statement to create things such as create a single node/multiple nodes, create a node with a label/various labels, create a node with properties and returning the created node.

In Neo4j, the files are storage persisted for long term durability. All the data related file are located inside the Neo4j data directory - data/databases/graph.DB (v3.x+) by default.

In Neo4j, CQL or Cypher Query Language is a query language or Neo4j Graph Database, CQL is a declarative pattern machining language which follows SQL like syntax. CQL has read, write and general clauses. It is used to define properties of a relationship or a node.

In Neo4j, the object cache caches individual relationships and nodes and respectively their properties in a form which is optimized for traversal of the graph. Here contents of this cache are objects with a representation geared towards the Neo4j supporting object API and graph traversals.

In Neo4j, an index is a redundant copy of data in the database purposed of making related data searches more efficient. It comes with the cost of additional storage space and slower writes, so deciding what to index and what not to is a crucial and often non-trivial task for users.

The MATCH command allows developers to specify patterns that Neo4j will search for in the database. This is the original way of getting data into the current set of buildings. It’s often paired with a WHERE clause which predicates or adds restrictions to the MATCH command.

• Neo4j CQL MATCH command – used to get data about nodes and properties

          MATCH

          (

           <node-name >:<label-name>

          )

• Delete all nodes and relationships command:

To create a new database in Neo4j without removing your existing one, users can directly edit the neo4j.conf file in their conf directory of their $NEO4J_HOME. Search dbms.active_database= and replace it with your desired name and restart the program again. A new database will be created now.

To delete a node in Neo4j, we have to use the DELETE clause. It also can be used to delete

relationships or paths. The syntax will be as following to delete a single node:

MATCH (n:Person { name: 'UNKNOWN' })

DELETE n

To delete all nodes:

MATCH (n)

DETACH DELETE n

The Set clause in Neo4j can be used to add new properties to an existing relationship or node. It can

also be used to update or add existing properties values. To set a property in a node, here is