Using MERGE w/ ON CREATE SET vs MERGE

General Newbie Questions
#1

Hi new here. I am following the guide (Tutorial: Import Relational Data Into Neo4j - Developer Guides) on importing CSV files into the graph database using the Northwind products.csv file as an example.

The sample code provided in the guide is:

/ LOAD CSV WITH HEADERS FROM 'file:///products.csv' AS row
MERGE (product:Product {productID: row.ProductID})
ON CREATE SET product.productName = row.ProductName, product.unitPrice = toFloat(row.UnitPrice); / using this code takes appox. 27 ms on my machine to create the nodes and properties

I've created the exact same result using MERGE only:

/LOAD CSV WITH HEADERS FROM 'file:///products.csv' AS row
MERGE (product:Product {productID: row.ProductID, productName:row.ProductName, unitPrice:toFloat(row.UnitPrice)}) / using this code takes appox. 60 ms on my machine to create the nodes and properties

Is there an advantage or best practice in using one over the other or is it pretty much the same thing?

Thx Josh

#2

the 2 statements are slightly different in that the first simply is asking to find a node with label :Product and which has a productID of row.ProductID. The 2nd statement is asking to find a node with label :Product and which has a productID of row.ProductID AND also has a productName equal to row.ProductName AND unitPrice equal to row.UnitPrice

#3

Thx for the reply Dana after reading your comment it seems to me my confusion was in the MERGE clause. I was starting with a blank database so I kept thinking MERGE was only to create new nodes; instead of MERGE as trying to first find if those nodes with properties exist in my current database, and if not, create them.