I had the graphical database created a while ago and I found that my Person nodes does not have an ID. Is it possible to generate an unique id for the existing nodes? I see when I use neo4j browser, there is an auto generated ID for graph view but the ID is not in the database.
Let me know if a Cypher query can do something like this:
MATCH (p:Person)
WHERE NOT p.id
SET p.id = AUTO_GEN_ID
RETURN p
so the new nodes would be modified?
All nodes have an automatically-generated "native ID" (that can be obtained via the ID function), but that native ID can be re-used for another node if the original node is deleted. To avoid confusion, it is best practice to add your own property (e.g., id, or uuid) if you need a unique ID.
You can use apoc.create.uuid to create a UUID. For example:
MATCH (p:Person)
WHERE NOT EXISTS(p.id)
SET p.id = apoc.create.uuid()
RETURN p
The APOC library can also automatically assign a UUID to a given property when a node with a specified label is created.
You can pass and 'unique' id via the language that you are using, just lookup uuid for you technology.
to be 100% sure that the codes are unique you have to pre-generate them or have counter that is thread-safe.