Thanks for all your answers, Everything said makes sense. I will get back to you guys with what we end up doing in case it is of any value for anyone else.
2010/1/4 Craig Taverner <cr...@amanzi.com>: > I think a generic solution would mean a generic numerical index. > > I wrote an index recently that is very similar in principle to the timeline > index Tobias mentioned below, except I allow multiple dimensions and > indexing over any numerical primitive type. Then we get to the next point, > combining indexes. Like in Tobias example: "give me all nodes where x=15 > ordered by y". This requires an index that works on x and y at the same > time. Otherwise you have to index one, and do a brute force search on the > other in the result set. > > I have an idea about dynamically generating a combined index based on > queries received by the database. So if the user does a query like the one > above, involving both x and y, and both of these are indexed, then a > combined index can be added dynamically. The first query will not be fast, > but subsequent ones would be. > > And as far as I can see, a combined index should be as simple as linking > nodes between the un-combined indexes. Now who's up for a n-way combination > of k-dimensional indexes? I think I'm getting a headache just thinking about > it :-) > > On Mon, Jan 4, 2010 at 10:17 AM, Raul Raja Martinez <raulr...@gmail.com>wrote: > >> Hi Tobias, >> >> Thanks for the info! >> >> I understand the implications of returning ordered nodes. >> Do you guys plan to build such support natively to neo4j even if it is >> for a basic set of node properties? >> >> While retrieving results ordered by property values or more extensive >> queries capabilities is provably not easy when dealing with a graph, >> it is currently one of >> the main things a programmer encounters when comparing neo4j to >> relational databases for storage and info retrieval. >> >> Would it make sense to have something like >> node.setOrderedProperty(property, value); so that the linked list >> based on the natural order of the value is kept internally by neo4j >> and then have another param in the traversers to specify that the >> traversal should follow the relationships established by the ordered >> linked nodes? >> >> If you guys think ordering based on property is out of the scope >> that's fine, I'm just asking in case we can avoid having to roll our >> own hack or component to get it working since ordered entities is a >> requirement in all of our current projects where we plan to use neo4j >> >> Thanks >> >> Raul >> >> >> 2010/1/4 Tobias Ivarsson <tobias.ivars...@neotechnology.com>: >> > Getting ordered results from any system always requires sorting, unless >> the >> > ordering property is stored. And sorting always requires (at least) O(n) >> > memory and O( log(n!) ) time for comparison sort, possibly O( n ) time >> for >> > sorting integer keys. >> > >> > So if you want results to be sorted on an arbitrary property you will >> have >> > to sort the entire result set and keep it around during your pagination >> > process (possibly redoing the query + entire sorting + skipping a few >> pages, >> > to preserve memory). >> > >> > If you know which properties you will want to order your results by when >> you >> > are designing your database you can store the ordering information in the >> > database. I would suggest a linked list of relationships in between the >> > nodes, in the natural order for the sorting property. >> > >> > You need to be aware of two things with this approach though. >> > The first one is that if the sorting property is unrelated to the >> filtering >> > property, if you want something like "give me all nodes where x=15 >> ordered >> > by y", you will either have to store separate linked lists for each value >> of >> > x, filter the result set while traversing through the results as they are >> > ordered by y, or revert to the sorting approach. >> > The second thing to be aware of is that insertion (and changing the value >> of >> > the ordering property in some node) will require some overhead, to >> preserve >> > the order. >> > >> > If your queries are as simple as "give me all nodes where x>LOWER_LIMIT >> and >> > x<UPPER_LIMIT ordered by x", and you can reduce the x property to a long >> > integer value, then the timeline index will do this for you. Otherwise >> there >> > is no ready made component for this today. >> > >> > Happy hacking, >> > Tobias >> > >> > On Mon, Jan 4, 2010 at 1:30 AM, Raul Raja Martinez <raulr...@gmail.com >> >wrote: >> > >> >> Hi, >> >> >> >> Anybody has any experience returning indexed nodes ordered by a given >> >> property?. >> >> For example return all nodes ordered by creationDate. I understand that >> if >> >> the node property is not indexed I'd have to iterate over all nodes >> first >> >> then order then limit the results which seems overkill to me. >> >> I'd like to be able to do... "get me all nodes from start to limit >> ordered >> >> by property". >> >> This is necessary when the data is iterated over using pagination and >> the >> >> order determines what the next start node is next. >> >> _______________________________________________ >> >> Neo mailing list >> >> User@lists.neo4j.org >> >> https://lists.neo4j.org/mailman/listinfo/user >> >> >> > >> > >> > >> > -- >> > Tobias Ivarsson <tobias.ivars...@neotechnology.com> >> > Hacker, Neo Technology >> > www.neotechnology.com >> > Cellphone: +46 706 534857 >> > _______________________________________________ >> > Neo mailing list >> > User@lists.neo4j.org >> > https://lists.neo4j.org/mailman/listinfo/user >> > >> >> >> >> -- >> Raul Raja >> _______________________________________________ >> 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 > -- Raul Raja _______________________________________________ Neo mailing list User@lists.neo4j.org https://lists.neo4j.org/mailman/listinfo/user
