neo4j data insertion taking time - neo4j

Question

I have installed Neo4j community Edition 3.0.3 on Ubuntu 14.04 on a linux local server and have successfully installed it. Now I am accessing it through my windows browser through the port 7474 on that server.
Now I have a csv file having sales order data in the following format:
Customer_id, Item_id, Order_Date
It has 90000 rows, and both customer_id and item_id are the nodes. A total of (30000 customer_ids + 30000 item_ids) nodes and 90000 relationships(order_date as the distance attribute name). I ran the below query to insert the data from csv to my graph database:
LOAD CSV WITH HEADERS FROM "file:///test.csv" AS line
MERGE (n:MyNode {Name:line.Customer})
MERGE (m:MyNode {Name:line.Item})
MERGE (n) -[:TO {dist:line.OrderDate}]-> (m)
I left it to run, and after around 7 to 8 hours, it was still running. My question is, am I doing anything wrong? is my query not optimized? or is this thing usual? I am new to both Neo4j and Cypher. Please help me on this.

Answer 1

Create a uniqueness constraint
You should create a uniqueness constraint on MyNode.Name:
CREATE CONSTRAINT ON (m:MyNode) ASSERT m.Name IS UNIQUE;
In addition to enforcing the data integrity / uniqueness of MyNode, that will create an index on MyNode.Name which will speed the lookups on the MERGE statements. There's a bit more info in the indexes and performance section here.
Using periodic commit
Since Neo4j is a transactional database, the results of your query is built up in memory and the entire query is committed at once. Depending on the size of the data / resources available on your machine you may want to use the periodic commit functionality in LOAD CSV to avoid building up the entire statement in memory. Just start your query with USING PERIODIC COMMIT. This will commit the results periodically, freeing memory resources while iterating through your CSV file.
Avoiding the eager
One problem with your query is that is contains an eager operation. This will hinder the periodic commit functionality and the transaction will all be built up into memory regardless. To avoid the eager operation you can use two passes through the csv file:
Once to create the nodes:
USING PERIODIC COMMIT
LOAD CSV WITH HEADERS FROM "file:///test.csv" AS line
MERGE (n:MyNode {Name:line.Customer})
MERGE (m:MyNode {Name:line.Item})
Then again to create the relationships:
LOAD CSV WITH HEADERS FROM "file:///test.csv" AS line
MATCH (n:MyNode {Name:line.Customer})
MATCH (m:MyNode {Name:line.Item})
MERGE (n) -[:TO {dist:line.OrderDate}]-> (m)
See these two posts for more info about the eager operation.
At a minimum you need to create the uniqueness constraint - that should be enough to increase the performance of your LOAD CSV statement.