Actually, we do have the case (due to an indexing/tagging model that can span many diverse "types") where we do not have knowledge within the domain model of the specific "type" of entity represented by a node at one end of a relationship, thus the reason for marking them with a "type" property....
-----Original Message----- From: user-boun...@lists.neo4j.org [mailto:user-boun...@lists.neo4j.org] On Behalf Of Mattias Persson Sent: Monday, March 01, 2010 4:25 AM To: Neo user discussions Subject: Re: [Neo] Typing of nodes (WAS: Java outof 64 GB ram) 2010/2/26 <rick.bullo...@burningskysoftware.com>: > Hi, Mattias. > > > > We had a similar requirement (to track the "type" of a node), and while > we were able to achieve this with relationships in very constrained > scenarios, we could not do so in a more general sense. Let me explain > and maybe you can suggest some ideas. > > > > We have "collections" of typed entities: dogs, trees, cars. Each "dog" > node relates to a "dogs" node, which in turn relates to the root node. > This way, we can easily traverse all of the "dogs" and "trees", etc... > > > > Imagine then a collection of "locations". Dogs, trees, and cars can be > related to a location. Thus, we can find all of the entities > associated with a specific location. However, when we traverse these > relationships from location to other entities, we lose the "type-ness", > since all we have is a generic node identity at the end of the > relationship. We thought about iterating through a series of > "hasSingleRelationship" checks on all of the known "type" relationships > on the node, but that seemed excessive. Thus, we now set a property > on each node that corresponds to the string representation > (enum.name()) for its "type" relationship. We avoided using the > ordinal of the enum as the property since that could be fragile and > also to make the property more "readable" during debugging. > Sure, it you go with a more generic relationship type then of course you'll have to store that information as f.ex. a property instead. These kind of types "dog", "cat", "car" or whatever suits better with properties, whereas domain model types, such as User or Group or Organisation can be great with only relationship types. So there's a difference between types and types, if you know what I mean. And it's not like you randomly grab a domain model object's node and try to find out its type... usually you hop one relationship (or some) and typically know roughly what you're landing at, so in such cases you won't have to iterate through ALL your types and do getSingleRelationship to figure out its type. > > > One advantage of this approach is that it is very easy to "invert" this > String property using enum.valueOf() to turn it back into the > underlying relationship type enum (for faster comparisons, different > types of traversals, etc.). Another is that it provides a much easier > way to deal with import/export of graph subsets since we can infer > directly from the node what it is and how to serialize/deserialize it > to XML, JSON, etc. I haven't looked at the source code for the various > POJO<->Neo libraries, but I'd suspect that they have to tag the node > with a "type" property as well. > > > > Thus far, it seems to work well. I welcome your thoughts as to > alternative approaches, however. > > > > Rick > > -------- Original Message -------- > Subject: Re: [Neo] Java outof 64 GB ram > From: Mattias Persson <matt...@neotechnology.com> > Date: Fri, February 26, 2010 5:11 am > To: Neo user discussions <user@lists.neo4j.org> > 2010/2/26 Miguel Ãngel Ãguila <magu...@ac.upc.edu>: > > I will explain me better. > > Every node has: > > - One String that have 5 chars. > > - One String that have 3 chars. > > - One String that have 4 chars. > > - One String that have 100 chars. > Is one of them any kind of "node type"? Because often you can infer a > type from its relationships or surrounding environment, making that > property redundant in a way. (nodes can often represent one or more > logical entities, hence a single type wouldn't suffice and that's why > it isn't built in to the API). > > > > Mike > > > > El vie, 26-02-2010 a las 10:05 +0100, Miguel Ãngel Ãguila Lorente > > escribió: > >> I don't know if I'm answering your question but every node has 4 > pairs > >> of String, therefore 4 pairs of char(15). > >> > >> Mike > >> > >> > >> > >> El jue, 25-02-2010 a las 07:18 -0700, > >> rick.bullo...@burningskysoftware.com escribió: > >> > Yes, exactly the question. If it's a big string, it is quite > possible > >> > to have the file grow this large. > >> > > >> > > >> > > >> > Miguel, approximately how long is the property value? > >> > > >> > > >> > > >> > -------- Original Message -------- > >> > Subject: Re: [Neo] Java outof 64 GB ram > >> > From: Johan Svensson <jo...@neotechnology.com> > >> > Date: Thu, February 25, 2010 7:13 am > >> > To: Neo user discussions <user@lists.neo4j.org> > >> > If you store 322M strings (one string property/relationship), > were > >> > each string is 200 bytes, the string store will be 60GB+ in > size. > >> > How large are the strings you are storing? > >> > -Johan > >> > On Thu, Feb 25, 2010 at 2:55 PM, > <rick.bullo...@burningskysoftware.com> > >> > wrote: > >> > > The string propertystore file seems really, really large to > me, > >> > based > >> > > on the # of nodes/relationships/properties. The reason I > ask is > >> > that I > >> > > saw similar behavior in some of our early testing. > Extremely large > >> > > string propertystores file. It would be helpful to > understand why > >> > the > >> > > file gets that large, and whether it is related to some of > the > >> > memory > >> > > stress issues. > >> > > > >> > > > >> > > > >> > > > >> > > > >> > > -------- Original Message -------- > >> > > Subject: Re: [Neo] Java outof 64 GB ram > >> > > From: Miguel ngel_guila Lorente <magu...@ac.upc.edu> > >> > > Date: Thu, February 25, 2010 1:57 am > >> > > To: Neo user discussions <user@lists.neo4j.org> > >> > > There are 322 million relationships, no 57 million > relationships. > >> > The > >> > > only propierty I save in the relationship is a String. In > this 322 > >> > > million relationships there are 3 diferents types of > relations. > >> > > Do you think that 13 GB is a strange number? Why? > >> > _______________________________________________ > >> > Neo mailing list > >> > User@lists.neo4j.org > >> > [1][1]https://lists.neo4j.org/mailman/listinfo/user > >> > > >> > References > >> > > >> > 1. [2]https://lists.neo4j.org/mailman/listinfo/user > >> > _______________________________________________ > >> > Neo mailing list > >> > User@lists.neo4j.org > >> > [3]https://lists.neo4j.org/mailman/listinfo/user > >> > >> > >> _______________________________________________ > >> Neo mailing list > >> User@lists.neo4j.org > >> [4]https://lists.neo4j.org/mailman/listinfo/user > > > > > > _______________________________________________ > > Neo mailing list > > User@lists.neo4j.org > > [5]https://lists.neo4j.org/mailman/listinfo/user > > > -- > Mattias Persson, [matt...@neotechnology.com] > Neo Technology, [6]www.neotechnology.com > _______________________________________________ > Neo mailing list > User@lists.neo4j.org > [7]https://lists.neo4j.org/mailman/listinfo/user > > References > > 1. https://lists.neo4j.org/mailman/listinfo/user > 2. https://lists.neo4j.org/mailman/listinfo/user > 3. https://lists.neo4j.org/mailman/listinfo/user > 4. https://lists.neo4j.org/mailman/listinfo/user > 5. https://lists.neo4j.org/mailman/listinfo/user > 6. http://www.neotechnology.com/ > 7. https://lists.neo4j.org/mailman/listinfo/user > > _______________________________________________ > Neo mailing list > User@lists.neo4j.org > https://lists.neo4j.org/mailman/listinfo/user > > -- Mattias Persson, [matt...@neotechnology.com] Neo Technology, www.neotechnology.com _______________________________________________ Neo mailing list User@lists.neo4j.org https://lists.neo4j.org/mailman/listinfo/user _______________________________________________ Neo mailing list User@lists.neo4j.org https://lists.neo4j.org/mailman/listinfo/user
