LOAD CSV Basics in Neo4j

Introduction

The LOAD CSV command in Neo4j is a powerful tool for importing data from CSV files into your graph database. This lesson covers the essentials of using LOAD CSV, including its syntax, common use cases, and best practices for efficient data loading.

Key Concepts

What is CSV?

CSV (Comma-Separated Values) is a simple file format used to store tabular data, such as a spreadsheet or database. Each line of the file corresponds to a data record, and each record consists of fields separated by commas.

Neo4j and CSV

Neo4j allows users to import data in a structured format through the LOAD CSV command. This command helps to create nodes and relationships from the CSV data easily.

Step-by-Step Process

Note: Ensure that your CSV file is accessible to the Neo4j server. If running locally, the file path should be relative to the Neo4j import directory.

Step 1: Prepare Your CSV File

Ensure your CSV file is formatted correctly. For example:

name,age
Alice,30
Bob,25
Charlie,35

Step 2: Use LOAD CSV

Here’s a basic example of how to use LOAD CSV to create nodes:

LOAD CSV WITH HEADERS FROM 'file:///yourfile.csv' AS row
CREATE (n:Person {name: row.name, age: toInteger(row.age)})

Step 3: Creating Relationships

To create relationships, you may need to load multiple CSV files:

LOAD CSV WITH HEADERS FROM 'file:///friends.csv' AS row
MATCH (a:Person {name: row.name1}), (b:Person {name: row.name2})
CREATE (a)-[:FRIENDS_WITH]->(b)

Best Practices

Always use headers in your CSV to improve readability and maintainability.
Use WITH to manage large datasets and avoid memory issues.
Test with a small subset of your data before scaling up the import.
Consider using transactions for batch operations to ensure data integrity.

FAQ

What if my CSV file has special characters?

Ensure that your CSV file is UTF-8 encoded. Neo4j can handle special characters as long as the encoding is correct.

Can I use LOAD CSV to update existing nodes?

Yes, you can use LOAD CSV to match existing nodes and update their properties using the SET clause.

What is the maximum file size I can load?

The maximum size depends on your system's memory. However, it’s advisable to split large files into smaller chunks for better performance.