Sorry for my bad english :)
I mean , In my application , There will be 10~20 millions nodes, and between one node to the other, there will be 10~20 thousands relations, I wonder what should the index be created for ? In other words, what the sizes of the index will not cause a File I/O ? which factors will cause this problem? Do I make it clearer? May be I should improve my English ------------------ 原始邮件 ------------------ 发件人: "Tobias Ivarsson"<[email protected]>; 发送时间: 2011年3月23日(星期三) 下午5:58 收件人: "Neo4j user discussions"<[email protected]>; 主题: Re: [Neo4j]回复： neo4j reade with getNodeById && index.with... Why not just keep the reference to the actual Node object then? Neo4j's internal cache and memory management makes this really cheap to do. [1] As to your questions about size of property of an index and maximum memory, you will have to be clearer, I really don't understand what you are asking for. -tobias [1] a Node object always occupies exactly 32B in a 64bit JVM, and I believe that would translate to 20B on a 32bit JVM. The actual state of the Node is stored internally in Neo4j and managed through the Neo4j cache. 2011/3/23 孤竹 <[email protected]> > Yes, I know I can't assign the IDS. But I can got some node's ID ,and cache > it in some place( i.e. in the cache). > > > when I need to search something , I got the id in the cache . Is it better > ? > > > At last, I wonder what size is property of the index? Depends On the memory > I gived to Neo4j ? > > > Is there a suggest rate ? for example , If the max-memory for Neo4j is 1G, > and the index is better less than 500M ? > > > ------------------ 原始邮件 ------------------ > 发件人: "mattias"<[email protected]>; > 发送时间: 2011年3月23日(星期三) 下午4:24 > 收件人: "Neo4j user discussions"<[email protected]>; > > 主题: Re: [Neo4j] neo4j reade with getNodeById && index.with... > > > And also to circumvent this different in performance for not-very-big > indexes you can make use of the built-in caching (for the new API)... see > > http://docs.neo4j.org/chunked/snapshot/indexing-lucene-extras.html#indexing-lucene-caching > > 2011/3/23 Tobias Ivarsson <[email protected]> > > > It is correct that getNodeById is much faster than an index lookup, but > IDs > > are assigned by Neo4j, there is no way for you as a user to assign IDs, > > which makes it a very blunt tool for looking up entities. To know which > id > > corresponds to a particular name or similar attribute, you would have to > go > > through an index, and that is exactly what the Neo4j index API does for > > you. > > > > By the way, the LuceneIndexService is a deprecated API, use > > GraphDatabaseService#index() instead: > > > > > http://components.neo4j.org/neo4j/1.3.M04/apidocs/org/neo4j/graphdb/GraphDatabaseService.html#index() > > > > Cheers, > > Tobias > > > > On Wed, Mar 23, 2011 at 3:45 AM, 孤竹 <[email protected]> wrote: > > > > > HI,all > > > > > > I Found something interesting, The test as follow: > > > > > > public static void main(String args[]) { > > > GraphDatabaseService db = new EmbeddedGraphDatabase("testDB"); > > > indexService = new LuceneIndexService(db); > > > Long startTime = System.currentTimeMillis(); > > > for(int i =0 ;i <10000;i++){ > > > Node node = getNodeByIndexProperty(db,String.valueOf(i)); > > > } > > > Long endTime = System.currentTimeMillis(); > > > System.out.println("time = " + (endTime - startTime)); > > > } > > > public static Node getNodeByIndexProperty(GraphDatabaseService db, > > > String keyValue) { > > > // Node node = indexService.getSingleNode(KEY_NAME, keyValue); > > > Node node = db.getNodeById(Long.valueOf(keyValue)); > > > return node; > > > } > > > > > > When I try to use the method indexService.getSingleNode...... with 9999 > > > times, It will take 2 seconds (nearly) , BY when I use > db.getNodeById.... > > > same times, It just take 350 millisecond . Does it mean getById is > faster > > > than use index ? or Does that mean the natural index is better than > index > > if > > > I can use it ? > > > > > > thanks for your help ,and replies, that help me very much! > > > _______________________________________________ > > > Neo4j mailing list > > > [email protected] > > > https://lists.neo4j.org/mailman/listinfo/user > > > > > > > > > > > -- > > Tobias Ivarsson <[email protected]> > > Hacker, Neo Technology > > www.neotechnology.com > > Cellphone: +46 706 534857 > > _______________________________________________ > > Neo4j mailing list > > [email protected] > > https://lists.neo4j.org/mailman/listinfo/user > > > > > > -- > Mattias Persson, [[email protected]] > Hacker, Neo Technology > www.neotechnology.com > _______________________________________________ > Neo4j mailing list > [email protected] > https://lists.neo4j.org/mailman/listinfo/user > _______________________________________________ > Neo4j mailing list > [email protected] > https://lists.neo4j.org/mailman/listinfo/user > -- Tobias Ivarsson <[email protected]> Hacker, Neo Technology www.neotechnology.com Cellphone: +46 706 534857 _______________________________________________ Neo4j mailing list [email protected] https://lists.neo4j.org/mailman/listinfo/user _______________________________________________ Neo4j mailing list [email protected] https://lists.neo4j.org/mailman/listinfo/user
