how can do an 'OR' search in NEO4J cypher - neo4j

Question

I have a Neo4j db with different labels on the nodes such as a:Banker , b:Customer. each has an email property I want to search for an email but but not search the entire db. So I want to do something like this Match(a:Banker {email: '123#mymail.com'}) OR Match (b:Customer {email:'123#mymail.com'}). There are constraints on email for both labels but I don't want each label to have the same email so before I add a node I need to determine if the email exist in either Banker or Customer nodes. I suspect this can be done in a very efficient scalable way that would not leave the user staring at a spinner when trying to add the one millionth record.....any help would be much appreciated

Answer 1

How I would do it is have an addition label 'Person' on all Bankers and Customers.
CREATE CONSTRAINT ON (b:Person) ASSERT p.Email IS UNIQUE
CREATE CONSTRAINT ON (b:Banker) ASSERT p.Email IS UNIQUE
CREATE CONSTRAINT ON (b:Customer) ASSERT p.Email IS UNIQUE
CREATE (b:Person:Banker {Email: "123#mymail.com"})
CREATE (b:Person:Customer {Email: "321#mymail.com"})
CREATE (c:Person:Customer {Email: "123#mymail.com"})
The last one will fail as a Person/Banker already has the same email. You can then also search MATCH (p:Person {Email: "123#mymail.com"}) or even b:Banker, c:Customer
You can also do (p:Person:Customer:Banker) if a person is all three.
It will also allow you to do MERGE which creates an entry if it doesn't already exist.
Since you already have a database you can do:
MATCH(b:Banker)
SET b:Person
MATCH(c:Customer)
SET c:Person

Answer 2

A somewhat "safer" approach than #Liam's would be to just have the Person label, without the Banker and Customer labels. That way, it would be harder to accidentally create/merge a node without the Person label, since that would be the only label for a person. Also, this approach would not require 2 (or 3) uniqueness checks every time you added a person.
With this approach, you could also add isCustomer and isBanker boolean properties, as needed, and create indexes on :Person(isCustomer) and :Person(isBanker) to quickly locate customers versus bankers.
Now, having said the above, I wonder if you really need the isCustomer and isBanker properties (or the Customer and Banker labels) at all. That is, the fact that a Person node is a banker and/or a customer may be derivable from that node's relationships. It seems reasonable for your data model to contain Bank nodes with relationships between them and people. For example, in the following data model, b is a banker at "XYZ Bank", c is a customer, and bc is both:
(b:Person)-[:WORKS_AT]->(xyz:Bank {id:123, name: 'XYZ Bank'}),
(c:Person)-[:BANKS_AT]->(xyz),
(bc:Person)-[:BANKS_AT]->(xyz)<-[:WORKS_AT]-(bc)
This query would find all bankers:
MATCH (banker:Person)-[:WORKS_AT]->(:Bank)
RETURN banker;
This would find all customers:
MATCH (banker:Person)-[:BANKS_AT]->(:Bank)
RETURN banker;
This would find all bankers who are also customers at the same bank:
MATCH (both:Person)-[:WORKS_AT]->(:Bank)<-[:BANKS_AT]-(both)
RETURN both;