UUIDs

The library supports manual and automation generation of UUIDs, which can be stored as properties on nodes.

UUIDs are generated using the java randomUUID utility method, which generates a v4UUID.

Manual UUIDs

Table 1. Functions

apoc.create.uuid()

returns a UUID string
The following generates a UUID
RETURN apoc.create.uuid() AS uuid;
Table 2. Results
uuid

"1051af4f-b81d-4a76-8605-ecfb8ef703d5"
The following creates a Person node, using a UUID as the merging key:
MERGE (p:Person {id: apoc.create.uuid()})
SET p.firstName = "Michael", p.surname = "Hunger"
RETURN p
Table 3. Results
p

{"firstName":"Michael","surname":"Hunger","id":"5530953d-b85e-4939-b37f-a79d54b770a3"}

Automatic UUIDs

There are also procedures that handle automatic adding of UUID properties, via the UUID Handler Lifecycle. The UUID handler is a transaction event handler that automatically adds the UUID property to a provided label and for the provided property name. Please check the following documentation to an in-depth description.

Enable apoc.uuid.enabled=true or apoc.uuid.enabled.[DATABASE_NAME]=true in $NEO4J_HOME/config/apoc.conf first.

procedure

description

CALL apoc.uuid.install(label, {addToExistingNodes: true/false, uuidProperty: 'uuid'}) yield label, installed, properties, batchComputationResult

it will add the uuid transaction handler for the provided label and uuidProperty, in case the UUID handler is already present it will be replaced by the new one

CALL apoc.uuid.remove(label) yield label, installed, properties

remove previously added uuid handler and returns uuid information. All the existing uuid properties are left as-is

CALL apoc.uuid.removeAll() yield label, installed, properties

removes all previously added uuid handlers and returns uuids information. All the existing uuid properties are left as-is

CALL apoc.uuid.list() yield label, installed, properties

provides a list of all the uuid handlers installed with the related configuration

Config

config

type

description

addToExistingNodes

Boolean (default: true)

when installed, for the label provided, adds the UUID to the nodes already existing in your graph

uuidProperty

String (default: uuid)

the name of the UUID field

UUID Examples

First create a Constraint for the Label and the Property, if you try to add a uuid an error occured.

CREATE CONSTRAINT ON (person:Person)
ASSERT person.uuid IS UNIQUE

Add the uuid:

CALL apoc.uuid.install('Person')
YIELD label, installed, properties
RETURN label, installed, properties

The result is:

label installed properties batchComputationResult

"Person"

true

{uuidProperty → "uuid", addToExistingNodes → true}

{wasTerminated → false, count → 10, batches → 1, successes → 1, failedOps → 0, timeTaken → 0, operationErrors → {}, failedBatches → 0}

The result is Node Person that has 2 properties:

apoc.uuid.result

Get all the uuid installed, call the procedure as:

CALL apoc.uuid.list()
YIELD label, installed, properties
RETURN label, installed, properties

The result is:

label installed properties

"Person"

true

{uuidProperty → "uuid", addToExistingNodes → true}

Remove the uuid installed call the procedure as:

CALL apoc.uuid.remove('Person')
YIELD label, installed, properties
RETURN label, installed, properties

The result is:

label installed properties

"Person"

false

{uuidProperty → "uuid", addToExistingNodes → true}

You can also remove all the uuid installed call the procedure as:

CALL apoc.uuid.removeAll()
YIELD label, installed, properties
RETURN label, installed, properties

The result is:

label installed properties

"Person"

false

{uuidProperty → "uuid", addToExistingNodes → true}

Export metadata

To import uuids in another database (for example after a ./neo4j-admin backup and /neo4j-admin restore), please see the apoc.systemdb.export.metadata procedure.