Cypher: Bulk update of a property on many nodes

[Luanne Coutinho]

Hi,

I have a bunch of item nodes and each node has a property called "quantity". I have a map with data {itemId, quantity}
Is there a good way to just run one query and update the quantity for each specific item? Or do I have to do this item by item?

Using 1.8.1.

Thanks
Luanne

[Peter Neubauer]

Luanne,

well, maybe the easiest way is to generate Cypher SET statements from this and execute them via the neo4j-shell?

/peter

Cheers,

/peter neubauer

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Luanne

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[Luanne Coutinho]

Hi Peter,

This is data I receive from another service, and I've got to update it in our Neo4j db as part of a data sync process.
I could definitely generate multiple Cyphers and have them executed- was just wondering if it could be done using one cypher. The number of items to be updated in the batch will be 5000+, so that's a lot of queries to execute in turn.

Regards
Luanne

[Peter Neubauer]

Luanne,

I am thinking that if you use the neo4j shell, you can actually do BEGIN/COMMIT thus having maybe just one transaction. With parameters (Michaels is adding that right now) in that script, even the Cypher exectuion shoudl not be costly. See https://github.com/neo4j/neo4j/pull/560, should be in shortly.

What do the say, Michael?

/peter

Cheers,

/peter neubauer

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[Luanne Coutinho]

Dumb question--how do I do this from my web application? I am using embedded, running in Tomcat. The flow is: there's an activeMQ consumer that receives a message containing this data. We've got to pick it up and update the graph.
I'm missing something?

Thanks
Luanne

[Peter Neubauer]

In one message, you get a Map with all the to-be-updated properties?

Cheers,

/peter neubauer

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Neo4j 1.8 GA - http://www.dzone.com/links/neo4j_18_release_fluent_graph_literacy.html

[Luanne Coutinho]

Yes. Key=id of the entity (already indexed in our graph), value=property value to be set

[Peter Neubauer]

Maybe generate a bunch of queries, like

start n = node:entities(id={key}) set n.property={value}

key and value as parameters, then loop over all the entries, and just modify the parameters for each with the same statement, open a transaction around all of them in embedded Java? Cypher does not handle TX on its own, that is a concern of the surrounding system.

/peter

Cheers,

/peter neubauer

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[Luanne Coutinho]

Yeah, that's what I ended up doing...thought I'd ask here too in case you guys had any magic :-)

Thanks Peter.

[Peter Neubauer]

Probably Michael or Wes can do some crazy stuff with the collection support in cypher, but this would be my Joe Corporate approach first ;)

/peter

[Michael Hunger]

How many are those?

You can do crazy stuff with

Pass two params, a list of id's to start

And a list of tuples id,value

And then

Start n=node({ids})

Set n.foo=last(head(filter(t in {tuples} : id(n)=head(t)))

Dunno if it is faster ;)

Mostly more complicated

Sent from mobile device

Am 27.02.2013 um 13:46 schrieb Peter Neubauer <peter.n...@neotechnology.com>:

Probably Michael or Wes can do some crazy stuff with the collection support in cypher, but this would be my Joe Corporate approach first ;)

/peter

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[Luanne Coutinho]

That looks really interesting- I'll amuse myself by deciphering it this weekend :-)
Thanks Michael!