Hi Evgeny, you may look at http://www.panFMP.org
This software uses a similar approach for very fast range queries without modifying Lucene. It works by storing the double values in a special encoded form with different precisions in the index, similar to the well known TRIEs. It may be very interesting to compare your algorithm with mine! Nice work, ----- Uwe Schindler H.-H.-Meier-Allee 63, D-28213 Bremen http://www.thetaphi.de eMail: [EMAIL PROTECTED] Hello, As part of my MSc project this summer I developed geoLucene, a modified version of Lucene (based on 2.3-dev checked out on 05.07) that can index geographical data using R-trees. It has been shown to be faster on geographic queries than the unmodified Lucene. The code is hosted at https://sourceforge.net/projects/geolucene/. This is an alpha release and it is not intended for production use. However, I hope somebody will find it useful and will develop it further. Though the code is far from being finished, I'm unable to continue developing this project. geoLucene is able to index documents in two indexes. First, a document is indexed using inverted index, as usual. Second, it may be (if developer wishes so) indexed using a spacial index, an R-tree. The spacial index can be searched and the results may be combined with the results from the inverted index. I'll explain how it works by providing the code. So, the search is done as follows: GeoSearchArea gsa = new GeoSearchArea(); gsa.setWest(x1); gsa.setEast(x2); gsa.setSouth(y1); gsa.setNorth(y2); GeoQuery geoQuery = new GeoQuery(gsa, searchMode); // geoQuery extends Query, search mode is intersection or enclosure IndexSearcher RTreeSearcher = new IndexSearcher(dir); Hits rTreeResults = RTreeSearcher.search(geoQuery); The data is indexed as follows: Document doc = new Document(); doc.add(new Field("latitude", Double.toString(lat), Field.Store.NO, Field.Index.UN_TOKENIZED)); doc.add(new Field("longitude", Double.toString(lon), Field.Store.NO, Field.Index.UN_TOKENIZED)); indexWriter.addDocument(doc); Here, "latitude" and "longitude" are hard-coded (recompile to change) field names that should contain geocoordinates. The documents that contain such coordinates are intercepted and indexed in an R-tree before being indexed in the inverted index. This project was a part of my MSc course. More details about the architecture, implementation and the performance results may be found in my MSc thesis available online: http://www.doc.ic.ac.uk/~es106/thesis/MultidimensionalIndexingInLucene.pdf. There is a web demo, which is available at http://geolucene.virtual.vps-host.net/ (IE, Firefox and latest Konqueror only). The web-demo runs in a multitasking environment (furthermore, the data is cached), so make a number of queries before averaging the search times. Examples of how to index and search files may be found in TestGeoSearchSpeed.java file (in the root directory of SVN repository). I used this file to run benchmarks. This project is still in alpha and there are many changes to be made before it can be called stable but I must warn you that it lacks one essential feature. I did not implement document deletion method. However, there is a not so complicated way of implementing it (preserving coherent document numbers in both indexes). It is described in the "Future Work" section of my thesis. Therefore, this version of the library can be tested to evaluate the performance of an R-tree (it's significantly faster than inverted index) only. As I've said in the beginning, I am unable to develop this project anymore, so I release it on SourceForge and I'm willing to pass the code to anybody who wants to improve it. There is no documentation but my thesis is a quite good (I hope) explanation of what's going on inside geoLucene. I'm happy to answer any queries and generally help with the project, if somebody wishes to develop it further. Regards, Evgeny Shadchnev --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
