LOAD CSV Advanced in Neo4j

1. Introduction

The LOAD CSV command in Neo4j is used to import data from CSV files into the database. This advanced lesson will explore various techniques and best practices to optimize your CSV loading processes, including handling large datasets, using headers for mapping, and more.

2. Key Concepts

Key Definitions

CSV (Comma-Separated Values): A file format that uses commas to separate values, often used for data exchange.
Transaction: A sequence of operations performed as a single logical unit of work.
Node: A fundamental unit of a graph, representing entities.
Relationship: A connection between two nodes, defining how they are related.

3. Step-by-Step Process

Note: Always back up your database before performing bulk imports.

Follow these steps to effectively use LOAD CSV for advanced data imports:

Prepare your CSV file ensuring proper formatting and encoding.
Use the LOAD CSV command with headers to map columns to properties.
Utilize WITH clauses to manage memory usage for large datasets.
Implement MERGE to avoid duplicates while creating nodes and relationships.
Commit changes in batches to optimize performance.

Code Example


LOAD CSV WITH HEADERS FROM 'file:///data.csv' AS row
MERGE (n:Person {name: row.name})
ON CREATE SET n.age = toInteger(row.age)
WITH n, row
MERGE (m:Movie {title: row.movie_title})
MERGE (n)-[:ACTED_IN]->(m);

4. Best Practices

Always validate your CSV data before importing.
Use indexes on frequently queried properties.
Load data in smaller batches for better performance.
Monitor memory usage and adjust settings accordingly.
Log errors during the import process for troubleshooting.

5. FAQ

What happens if my CSV file is too large?

Consider splitting the file into smaller chunks or using the USING PERIODIC COMMIT option to manage memory effectively.

Can I use LOAD CSV with remote files?

Yes, but you must enable access to the appropriate URL in the Neo4j configuration.

How do I handle missing values in my CSV?

You can use the COALESCE function to provide default values for missing properties.