I see, that makes sense, ty Does this code work the same for embedded single node and cluster high availability graph db's?
-----Original Message----- From: user-boun...@lists.neo4j.org [mailto:user-boun...@lists.neo4j.org] On Behalf Of Michael Hunger Sent: Sunday, August 07, 2011 1:04 PM To: Neo4j user discussions Subject: Re: [Neo4j] Unique Constaint on Index Just from my head. tx = graphdb.beginTransaction(); try { Node lockNode = graphdb.getReferenceNode(); // or another node that is used for locking this unique index lockNode.removeProperty("__non_existent_property__"); index=graphdb.index().forNodes("unique-name"); Node user = index.get("name",name).getSingle(); if (user==null) { user=graphdb.createNode(); user.setProperty("name",name); index.add(user,"name",name); } tx.success(); } finally { tx.finish(); } Am 07.08.2011 um 17:40 schrieb etc1: > Not sure I understand this: > A consistent, but hackish, attempt to acquire a cluster-wide lock is > to remove a non-existent node; what does this mean, exactly; code sample? > > > -----Original Message----- > From: user-boun...@lists.neo4j.org > [mailto:user-boun...@lists.neo4j.org] On Behalf Of etc3 > Sent: Thursday, July 07, 2011 11:49 AM > To: 'Neo4j user discussions' > Subject: Re: [Neo4j] Unique Constaint on Index > > I'm new to this framework, is there an example that demonstrates > removing a non-existent property and how it would be used in this context? > > Thanks > > -----Original Message----- > From: user-boun...@lists.neo4j.org > [mailto:user-boun...@lists.neo4j.org] On Behalf Of Chris Gioran > Sent: Thursday, July 07, 2011 11:04 AM > To: Neo4j user discussions > Subject: Re: [Neo4j] Unique Constaint on Index > > Hi, > > the ability to acquire locks cluster-wide exists, albeit in an ad hoc > fashion. Grabbing a write lock on the node you want to ensure is > uniquely indexed will ensure that the operations are serialized across > all cluster members. > The most simple way to get that lock currently is the (somewhat > hackish but entirely correct) removal of a non-existing property. > > cheers, > CG > > On Thu, Jul 7, 2011 at 5:53 PM, etc3 <e...@nextideapartners.com> wrote: >> How do I ensure another request is not performing the same operation >> on another node in the cluster? >> >> >> -----Original Message----- >> From: user-boun...@lists.neo4j.org >> [mailto:user-boun...@lists.neo4j.org] On Behalf Of Marko Rodriguez >> Sent: Thursday, July 07, 2011 10:35 AM >> To: Neo4j user discussions >> Subject: Re: [Neo4j] Unique Constaint on Index >> >> Hi, >> >>> We are testing Neo4J and need to support unique emails across all >>> users. Is this possible with the current API? >> >> You can add such a constraint when updating the indices: >> >> if(index.get('email', address).hasNext()) { throw new >> RuntimeException("There are two nodes that share the same email >> address."); } else { index.put('email', address, node); } >> >> Marko. >> >> http://markorodriguez.com >> _______________________________________________ >> Neo4j mailing list >> User@lists.neo4j.org >> https://lists.neo4j.org/mailman/listinfo/user >> >> _______________________________________________ >> Neo4j mailing list >> User@lists.neo4j.org >> https://lists.neo4j.org/mailman/listinfo/user >> > _______________________________________________ > Neo4j mailing list > User@lists.neo4j.org > https://lists.neo4j.org/mailman/listinfo/user > > _______________________________________________ > Neo4j mailing list > User@lists.neo4j.org > https://lists.neo4j.org/mailman/listinfo/user > > _______________________________________________ > Neo4j mailing list > User@lists.neo4j.org > https://lists.neo4j.org/mailman/listinfo/user _______________________________________________ Neo4j mailing list User@lists.neo4j.org https://lists.neo4j.org/mailman/listinfo/user _______________________________________________ Neo4j mailing list User@lists.neo4j.org https://lists.neo4j.org/mailman/listinfo/user
