I think we don't have to worry about backwards compatibility much yet. There has not been a formal release of the component, so if there are people using the software, they will accept that they are bleeding edgers. Indeed addNode should return the KEY_VALUE relationship and I think we should change the signature of SortedTree to turn it into Iterable<Relationship>. No need to maintain a Node iterator, the node is always one getEndNode away. Niels
> Date: Thu, 8 Sep 2011 14:17:59 +1200 > From: [email protected] > To: [email protected] > Subject: Re: [Neo4j] Issues with IndexedRelationship > > Will have to experiment with changing my id's to be stored as longs, it does > make perfect sense really that it would be better. Thanks for the hint. > > In regards to SortedTree returning the KEY_VALUE relationship instead of the > end Node, I had thought of that too, and it would definitely help. Could > end up being a significant change to SortedTree though, e.g.: > sortedTree.addNode( node ); > Would need to return the KEY_VALUE relationship instead of a boolean. Which > not knowing where else SortedTree is used could be a large change? > > Maybe SortedTree would have two iterator's available a key_value > relationship iterator, and a node iterator. Having a quick look at it now > it seems that it could work ok that way without introducing much code > duplication. > > On Thu, Sep 8, 2011 at 12:46 PM, Niels Hoogeveen > <[email protected]>wrote: > > > > > Two longs is certainly cheaper than a string. Two longs take 128 bit and > > are stored in the main record of the PropertyContainer, while a String would > > require a 64 bit "pointer" in the main record of the PropertyContainer, and > > an additional read in the String store where the string representation will > > take up 256 bits. So both memory-wise, as perfomance wise, it is better to > > store a UUID as two long values. > > > > > > The main issue is something that needs a deeper fix than adding ID's. > > SortedTree now returns Nodes when traversing the tree. We should however > > return the KEY_VALUE Relationship to the indexed Node. Then > > IndexedRelationship.DirectRelationship can be created with that relationship > > as an argument. We get the Direction and the RelationshipType for free. > > Niels > > > > > Date: Thu, 8 Sep 2011 11:36:11 +1200 > > > From: [email protected] > > > To: [email protected] > > > Subject: Re: [Neo4j] Issues with IndexedRelationship > > > > > > Hi Niels, > > > > > > Sorry I didn't quite write the bit about (1) clearly enough. The problem > > is > > > that it presently throws an Exception where it shouldn't. > > > > > > This stems from IndexedRelationship.DirectRelationship: > > > this.endRelationship = endNode.getSingleRelationship( > > > SortedTree.RelTypes.KEY_VALUE, Direction.INCOMING ); > > > > > > So if the end node has more than one incoming KEY_VALUE relationship a > > more > > > than one relationship exception is thrown. > > > > > > Instead of the getSingleRelationship I was planning on iterating over the > > > relationships and matching the UUID stored at the root end of the IR with > > > one of the KEY_VALUE relationships (which is why using a unique id is > > > necessary rather than the relationship type). Note: there will actually > > > still be an issue if the same IR has multiple relationships to the same > > leaf > > > node - still thinking about that might need . > > > > > > Is storing the UUID as two longs much quicker than storing it as a > > string? > > > Curious about this since in my current model I have all the domain > > objects > > > with UUID's, and these are all stored as strings. If it was going to > > help > > > with either memory or performance then I would be keen to migrate this to > > > two longs. > > > > > > Cheers > > > Bryce > > > > > > On Thu, Sep 8, 2011 at 11:07 AM, Niels Hoogeveen > > > <[email protected]>wrote: > > > > > > > > > > > Great work Bryce, > > > > I do have a question though. > > > > What is the rationale for the restriction mentioned under "1)". Do you > > need > > > > this for the general case (to make IndexedRelationshipExpander work > > > > correctly), or do you need it for your own application to throw that > > > > exception? If the latter is the case, I think it would be important to > > tease > > > > out the general case and offer this new behaviour as an option. > > > > A unique key for the index is a good idea anyway and can be added to > > > > SortedTree. Generate a UUID and store it in two long properties. That > > way > > > > the two values will always be read in the first fetch of the underlying > > > > PropertyContainer. A getId method on the TreeNodes can then return a > > String > > > > representation of of the two long values. > > > > IndexRelationships are a relatively new development, so I think you are > > one > > > > of the first to actually try it out. Personally I have chosen to > > directly > > > > work with SortedTree, because I am working within the framework of a > > wrapper > > > > API, so I can integrate the functionality behind the regular > > > > createRelationshipTo and getRelationships methods. > > > > I don't think API changes will be an issue at the moment. > > > > Niels > > > > > Date: Thu, 8 Sep 2011 10:22:11 +1200 > > > > > From: [email protected] > > > > > To: [email protected] > > > > > Subject: [Neo4j] Issues with IndexedRelationship > > > > > > > > > > Hi, > > > > > > > > > > As I mentioned a while ago I am looking at using > > IndexedRelationship's > > > > > within my application. The major thing that was missing for me to be > > > > able > > > > > to do this was IndexedRelationshipExpander being able to provide all > > the > > > > > relationships from the leaf end of indexed relationships through the > > the > > > > > root end. So I have been working on getting that support in there. > > > > > > > > > > However in writing this I have discovered a number of other issues > > that I > > > > > have also fixed, and at least one I am still working on. Since I was > > > > right > > > > > into the extra support for expanding the relationships it is hard to > > > > break > > > > > out these fixes as a separate commit (which I think would be ideal), > > so > > > > it > > > > > will most likely all come in together hopefully later today (NZ > > time). > > > > > > > > > > Just letting everyone know in case someone else is doing development > > > > against > > > > > indexed relationships. > > > > > > > > > > Quick run down of the issues, note: N -- IR(X) --> {A,B} below means > > > > there > > > > > is a indexed relationship from N to A & B, of type X. > > > > > > > > > > 1) Exception thrown when more than one IR terminates at a given node, > > > > e.g.: > > > > > N1 -- IR(X) --> {A,B,C,D} > > > > > N2 -- IR(X) --> {A,X,Y,Z} > > > > > Will throw an exception when using the IndexedRelationshipExpander on > > > > either > > > > > N1, or N2. > > > > > > > > > > 2) Start / End nodes are transposed when the IR has an direction of > > > > > incoming, i.e. the IR is created against N but across a set of > > incoming > > > > > relationships: > > > > > N <-- IR(Y) -- {A,B,C} > > > > > Will return 3 relationships N --> A, N --> B, N --> C. > > > > > > > > > > I have written tests for each of these, as well as a couple of other > > > > tests. > > > > > > > > > > Still completing (1) and have a little question about this. In order > > to > > > > fix > > > > > this I may need to introduce a unique ID stored against the IR both > > at > > > > the > > > > > root and at the leaves. Currently the relationship type is used to > > name > > > > the > > > > > IR at both root and leaves, but in the case above that means you > > can't > > > > tell > > > > > from node A which KEY_VALUE relationship belongs to which IR tree > > without > > > > > traversing the tree. > > > > > > > > > > So the question is adding this ID would mean that anyone who is > > already > > > > > using this wont have the ID, and therefore without care will be data > > > > > incompatible with the updated code. This could be managed via a > > check > > > > for > > > > > the ID when accessing the tree and if it isn't there doing a walk > > over > > > > the > > > > > tree to populate all the places where it is required. > > > > > > > > > > In general in developing against this code where do we sit on data > > > > > compatibility and API compatibility? > > > > > > > > > > Cheers > > > > > Bryce > > > > > _______________________________________________ > > > > > Neo4j mailing list > > > > > [email protected] > > > > > https://lists.neo4j.org/mailman/listinfo/user > > > > > > > > _______________________________________________ > > > > Neo4j mailing list > > > > [email protected] > > > > https://lists.neo4j.org/mailman/listinfo/user > > > > > > > _______________________________________________ > > > Neo4j mailing list > > > [email protected] > > > https://lists.neo4j.org/mailman/listinfo/user > > > > _______________________________________________ > > Neo4j mailing list > > [email protected] > > https://lists.neo4j.org/mailman/listinfo/user > > > _______________________________________________ > Neo4j mailing list > [email protected] > https://lists.neo4j.org/mailman/listinfo/user _______________________________________________ Neo4j mailing list [email protected] https://lists.neo4j.org/mailman/listinfo/user
