Neo4j Interview Questions & Answers

Question 1. What Is Neo4j?

Answer :

Neo4J is an open-source, schema-free, NoSQL, popular graph database. It is the world's leading open-source graph database.

Question 2. In Which Language Neo4g Is Written?

Answer :

Neo4J is written and implemented in Java language.

Question 3. Which Query Language Is Used By Neo4j?

Answer :

Cypher Query Language (CQL) is used by Neo4J.

Question 4. Which Was The Neo4j First Version And When Was It Released?

Answer :

The first version of Neo4J was Neo4j 1.0 and it was released in Feb, 2010.

Question 5. In Which Cases Neo4j Is Widely Used?

Answer :

Neo4J is widely used for:

• Highly connected data Social Network
• Recommendation- ( e-commerce)
• Path Finding
• Data First Schema (bottom-up)
• Schema Evolution
• A*(Least Cost Path)

Question 6. What Is The Role Of Building Blocks Like Nodes, Relationships, Properties And Labels In Neo4j?

Answer :

Roles of building blocks:

Nodes: They are entities equivalent to rows in table.

Relationship: It connects entities and structure domain.

Properties: It contains meta-data and attributes.

Labels: It groups nodes by role.

Question 7. Which Are The Several Popular Graph Databases?

Answer :

Neo4J is a very popular Graph Database. Other Graph Databases are Oracle NoSQL Database, OrientDB, HypherGraphDB, GraphBase, InfiniteGraph, AllegroGraph etc.

Question 8. How Files Are Stored In Neo4j?

Answer :

Neo4J stored graph data in a number of different store files, and each store file contains the data for a specific part of the graph for example relationships, nodes, properties etc.

Question 9. What Is Cql? How Can You Run Cql Commands In Neo4j?

Answer :

CQL stands for Cypher Query Language. You have to use "$" prompt to run all CQL commands in Neo4j.

Question 10. Which Query Language Does Neo4j Use And What It Contains?

Answer :

Neo4j uses Cypher query language, which is unique to Neo4j. If you want to traverse a graph, you have to know where you want to begin (Start), the rules that allow traversal (Match) and what data you are expecting back (Return).

The basic query contains:

START n

MATCH n-[r]- m

RETURN r;

Question 11. What Can You Delete Databases In Neo4j?

Answer :

If you want to delete/remove entire graph directory you can use command rm -rf data/*as such Neo4j is not storing anything outside that.

Question 12. Is It Possible To Query Neo4j Over The Internet?

Answer :

As such Neo4j got RESTful API, you can query over the web, or you can run it locally. It runs in the Heroku or Cloud.

Question 13. What Neo4j Cql Command Is Used For?

Answer :

Neo4j CQL command can be used for the following reasons:

• It is used to create nodes with and without properties.
• It is used to create a relationship between nodes with properties.
• It is used to create a relationship between nodes without properties.
• It is used to make multiple or single labels to a Node or a Relationship.

Question 14. What Is Match Command In Neo4j? Where Is It Used?

Answer :

Syntax for MATCH command:

MATCH  

(  

<node-name>:<label-name>  

)  

The MATCH command cannot be used alone to fetch data from the database otherwise it will show invalid syntax error.

Question 15. Why Is Set Clause Used For In Neo4j?

Answer :

In Neo4J CQL, SET clause is used for following purposes:

• Update or Add properties values.
• Add new properties to existing Relationship or Node.

Question 16. What Are The Indexing Capabilities Of Neo4j?

Answer :

Neo4j as a graph database features indexing as the preferred way to find start points for graph traversals. Over the years multiple different indexing approach have been added. The goal of this article is to give an overview on this to avoid confusion esp. for those who just recently got started with Neo4j.

A graph database using a property graph model stores its data in nodes, relationships and properties. In Neo4j 2.0 this model was amended with labels.

Neo4J supports no indexes in the beginning later it started support for manual ,automatic and schema indexes

Question 17. Explain For What Purpose You Can Use Neo4j Databases?

Answer :

following are some areas where you can use Neo4j Databases:

• For  Social Networks where data is highly connected.
• For creating Recommendation system in shopping websites.
• Algorithms used in pathfinding
• Data First Schema
• Schema Evolution

Question 18. List Some Neo4j Cql Command?

Answer :

Neo4j CQL is a query language for Neo4j Graph Database.Is a declarative pattern-matching language which follows SQL like syntax that are very simple and are in human readable format

Below are some Neo4j CQL command:

CREATE,MERGE,SET,RETURN,START,LOAD CSV,REMOVE,CREATE UNIQUE,UNWIND,UNION,CALL

Question 19. Why Neo4j Is Called Graph Database?

Answer :

Neo4J is called graph database because it saves data structure in graph rather than in tables.

Question 20. Is It Easy To Fragment A Neo4j Graph Across Multiple Servers?

Answer :

It is very difficult to fragment a Neo4J graph across multiple servers.