Some way to create 1 million relationships with a neo4j query - neo4j

Question

With this query I am importing 75000 nodes from my csv file. (Category)
USING PERIODIC COMMIT
LOAD CSV WITH HEADERS
FROM "file:///prodcategory.csv" AS row
CREATE (:Category {id: row.idProdCategory, name: row.name, idRestaurant: row.idRestaurant});
And with this query I am also importing 1 million nodes from my csv file (Product)
USING PERIODIC COMMIT
LOAD CSV WITH HEADERS
FROM "file:///products.csv" AS row
CREATE (:Product {id: row.idProduct, idProductCategory: row.idProductCategory,name: row.name,idRestaurant:row.idRestaurant ,description: row.description, price: row.price, shipping_price: row.shippingPrice});
I am using this query to create the relationship between id -> category and idProductCategory -> products.
MATCH (category:Category {id: category.id})
MATCH (Product:Product {idProductCategory: Product.idProductCategory})
WHERE Product.idProductCategory=category.id
MERGE (category)-[:OF_CATEGORY]->(Product);
This query only creates 2999 relationships and I do not believe the 1 million relationships I should create, please if there is a method or configuration to be able to create more than 1 million relationships please help me I would be very grateful.

Answer 1

Ensure you have indexes on Product.idProductCategory.
I assume that the category id is unique across categories.
CREATE CONSTRAINT ON (category:Category) ASSERT category.id IS UNIQUE;
I assume that there are multiple products with the same category ID.
CREATE INDEX ON :Product(idProductCategory);
Then you can simply match each category and then for each category find the appropriate products and create the relationships.
// match all of your categories
MATCH (category:Category)
// then with each category find all the products
WITH category
MATCH (Product:Product {idProductCategory: category.id })
// and then create the
MERGE (category)-[:OF_CATEGORY]->(Product);
If you are running into memory constraints you could use the APOC periodic commit to wrap your query...
call apoc.periodic.commit("
MATCH (category:Category)
WITH category
MATCH (Product:Product {idProductCategory: category.id })
MERGE (category)-[:OF_CATEGORY]->(Product)
",{limit:10000})

Answer 2

try to change your query to this... you are using too many filters in your query
check docs for MATCH
MATCH (category:Category),(Product:Product)
WHERE Product.idProductCategory=category.id
MERGE (category)-[:OF_CATEGORY]->(Product)
you can also just change your second import query, so you do not need a separate query for linking.
USING PERIODIC COMMIT
LOAD CSV WITH HEADERS
FROM "file:///products.csv" AS row
CREATE (p:Product {id: row.idProduct, name: row.name,idRestaurant:row.idRestaurant ,description: row.description, price: row.price, shipping_price: row.shippingPrice})
MATCH (c:Category{id:row.idProductCategory}
MERGE (p)-[:OF_CATEGORY]->(c)