Neo4j

AlbertGevorgyan · 02-01-2022

I am trying to merge a node, and then pass it to a custom procedure - but only the first time it is created. However, this doesn't work: MERGE (n:Any {id:1}) ON CREATE WITH n CALL my.procedure(n) Is there an alternative way to do this?

AlbertGevorgyan · 01-28-2022

According to the documentation, for the following update Neo4j automatically acquires a writing lock: MATCH (n:Example {id: 42}) SET n.prop = n.prop + 1 I have tested it as part of different queries. The first one returns the entire node and is actu...

AlbertGevorgyan · 01-25-2022

While testing with embedded, I am trying to merge a node labelled "Compound", and getting a very strange exception on the commit: "java.lang.IllegalStateException: This transaction is already being closed". The same query works fine with any other la...

AlbertGevorgyan · 01-20-2022

I am trying to import neo4j-cypher-dsl into an unmanaged server extension. I can start the extension but when I call the REST API method that uses DSL code I see the following error in the log: javax.servlet.ServletException: org.glassfish.jersey.ser...

AlbertGevorgyan · 01-13-2022

I have created a project that contains an ExtensionFactory subclass annotated as @ServiceProvider that returns a LifecycleAdapter subclass which registers a transaction event listener in its start() method, as shown in this example. The code is belo...

AlbertGevorgyan · 02-02-2022

Yes, this works indeed, thanks! To slightly simplify it, other (non-calculated) properties can be set directly in the ON CREATE clause: MERGE (n:Any {id:1}) ON CREATE SET n.created = true, n.property2=value2 WITH n CALL { WITH n WITH [i in [n]...

AlbertGevorgyan · 02-02-2022

I need to set multiple properties in ON CREATE (no just the one calculated by the procedure), and then return the node. So ideally it should be something like: MERGE (n:Any {id:1}) ON CREATE SET n.property = {value returned by a side-effectful proce...

AlbertGevorgyan · 02-02-2022

Thanks, this works. Would it be possible then to continue the query with ON SET and RETURN clauses? A RETURN in the end of this query only returns a newly created node, or null if it was matched.

AlbertGevorgyan · 02-01-2022

Thanks for your reply. Since my procedure itself calculates and sets a property, the simplest solution is to check if the property already exists in the procedure's body - the only downside is that this logic is hidden from the user. The other altern...

AlbertGevorgyan · 01-31-2022

Comparing the execution plans reveals potentially interesting differences: Returning node (thread safe): MATCH (n:Example {id: 42}) SET n.prop = n.prop + 1 RETURN n +------------------+------------------------------+----------------+ | Operator ...

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Call custom procedure ON CREATE

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