neo4j load csv taking infinite time to execute my query - neo4j

Question

I am loading the data into neo4j using loadcsv function. I have two types of nodes -Director and Company.
The below command is working fine and is executing within 50milisec.
LOAD CSV FROM "file:///Director.csv" AS line
CREATE(:Director {DirectorDIN:line[0]})
Load csv from "file:///Company.csv" AS line
Create(:Company{CompanyCIN:line[0]})
Now I am trying to build the relationship between the two nodes which is taking an infinite time to execute my query. Here is the simple query that I am trying.
LOAD CSV FROM "file:///CompanyDirector.csv" AS line
match(c:Company{CompanyCIN:toString(line[0])}),(d:Director{DirectorDIN:toString(line[1])}) create (c)-[:Directed_by]->(d)
I have also tried:
LOAD CSV FROM "file:///CompanyDirector.csv" AS line
match(c:Company{CompanyCIN:line[0]}),(d:Director{DirectorDIN:line[1]}) create (c)-[:Directed_by]->(d)
It is taking an infinite time. Please let me know what can be the issue over here?
Information:
The CSV file does not contain more than 20k records.
CompanyCIN is alphanumeric
DirectorDIN is numeric in nature

Answer 1

I think you forgot to create some schema constraint in your database :
CREATE CONSTRAINT on (n:Company) ASSERT n.CompanyCIN IS UNIQUE;
CREATE CONSTRAINT on (n:Director) ASSERT n.DirectorDIN IS UNIQUE;
Without thoses constraints the complexity of your query is N*M, where N is the number of Company nodes and M the number of Director.
To see what I mean, you can EXPLAIN your query before and after the creation of thoses constraints.
Moreover, you should also use the PERIODIC COMMIT on your LOAD CSV query, like that :
USING PERIODIC COMMIT 5000
LOAD CSV FROM "file:///CompanyDirector.csv" AS line
MATCH (c:Company{CompanyCIN:line[0]})
MATCH (d:Director{DirectorDIN:line[1]})
CREATE (c)-[:Directed_by]->(d)

Answer 2

The main issue was that you did not have indexes on :Company(CompanyCIN) and :Director{DirectorDIN). Without the indexes, neo4j is forced to evaluate every possible pair of Company and Director nodes for every line in your CSV file. That takes a lot of time.
CREATE INDEX ON :Company(CompanyCIN);
CREATE INDEX ON :Director{DirectorDIN);
By the way, creating the corresponding uniqueness constraints (as suggested by #logisma) has the side-effect of creating these indexes, but the issue was not caused by missing uniqueness constraints.
In addition, you should avoid creating duplicate Directed_by relationships by using MERGE instead of CREATE.
This should work better (you can use the USING PERIODIC COMMIT option, as suggested by #logisima if you have ):
USING PERIODIC COMMIT 5000 LOAD CSV FROM "file:///CompanyDirector.csv" AS line
MATCH (c:Company {CompanyCIN:line[0]})
MATCH (d:Director {DirectorDIN:line[1]})
MERGE (c)-[:Directed_by]->(d)