No iris not. One uses an index on disk. And one used an index in memory.
Jody On 13/01/2012, at 11:13 AM, Yang <[email protected]> wrote: > since I need to look up a latitude,longitude point, I need spatial > index, i.e. SpatialIndexFeatureCollection, but isn't this the > underlying structure utilized by IndexedShapeFileDataSource (which I'm > already using) ? > > thanks > Yang > > On Thu, Jan 12, 2012 at 2:01 PM, Jody Garnett <[email protected]> wrote: >> There are three implementations available for an in memory >> FeatureCollection. >> >> http://docs.geotools.org/latest/userguide/library/main/collection.html#performance-options >> >> -- >> Jody Garnett >> >> On Friday, 13 January 2012 at 6:50 AM, Mark Prins wrote: >> >> Op 12-Jan-12 21:10, Yang schreef: >> >> thanks, I did utilize the useMemoryMappedBuffer option. let me dig up >> the first one. >> >> by "copy all of the shapefile into a DataStore or feature store that >> uses a memory stucture " do you mean something like "MemoryDataStore" >> ( >> http://udig.refractions.net/files/docs/api-geotools/org/geotools/data/memory/MemoryDataStore.html >> ) ? so basically I need to iterate through all the features in my >> existing ShapeFileDataStore, and insert them into MemoryDataStore, and >> hopefully the later queries would be faster , right? sounds like a >> possible approach. >> >> >> yes, this would save using file io. i've never used memoryDataStore and >> the docs >> (http://docs.geotools.org/latest/userguide/library/data/memory.html) say >> it may be slow, so you may want to cook up one yourself. >> Maybe one of the SimpleFeatureCollection implementations together with >> subCollection(Filter) may also fit your need. >> >> >> actually I did a later test and put all my indexedShapeFileDataStore >> on a tmpfs mount (basically memory disk), and surprisingly the >> performance did not change much from direct disk access. most of the >> time is still spent on reading file buffers and opening index file >> readers >> >> >> this opening and closing of file handles is probably the most costly >> part. I try to steer away from shapefiles whenever I can. >> >> maybe one of the devs has something to say about this, but it's a bit >> difficult without you code. >> >> >> Yang >> >> On Thu, Jan 12, 2012 at 11:37 AM, Mark Prins<[email protected]> wrote: >> >> Op 12-Jan-12 01:36, Yang schreef: >> >> my code looks up features from a IndexedShapeFileDataStore >> >> basically: >> >> for(Point p : given points ) { >> dataStore.getFeature(query(p)); >> } >> >> >> I can see from "top" command that the RES memory consumption is only 40MB, >> I have about 8GB on the box, and have allocated -Xmx4000M to jvm. >> is there any way I could let geotools load more content into memory, >> so hopefully it would query faster? >> >> >> you could try to copy all of the shapefile into a DataStore or feature >> store that uses a memory stucture such as eg. a hashtable to create an >> in memory cache of the data, of course this will only work reliably in a >> read-only scenario. it depends on you data if it's worth the tradeoff >> with longer startup time. >> >> btw. don't the "cacheMemoryMaps" and "useMemoryMappedBuffer" options on >> IndexedShapeFileDataStore() do anything? >> >> >> ------------------------------------------------------------------------------ >> RSA(R) Conference 2012 >> Mar 27 - Feb 2 >> Save $400 by Jan. 27 >> Register now! >> http://p.sf.net/sfu/rsa-sfdev2dev2 >> _______________________________________________ >> Geotools-gt2-users mailing list >> [email protected] >> https://lists.sourceforge.net/lists/listinfo/geotools-gt2-users >> >> >> >> ------------------------------------------------------------------------------ >> RSA(R) Conference 2012 >> Mar 27 - Feb 2 >> Save $400 by Jan. 27 >> Register now! >> http://p.sf.net/sfu/rsa-sfdev2dev2 >> _______________________________________________ >> Geotools-gt2-users mailing list >> [email protected] >> https://lists.sourceforge.net/lists/listinfo/geotools-gt2-users >> >> >> >> ------------------------------------------------------------------------------ >> RSA(R) Conference 2012 >> Mar 27 - Feb 2 >> Save $400 by Jan. 27 >> Register now! >> http://p.sf.net/sfu/rsa-sfdev2dev2 >> _______________________________________________ >> Geotools-gt2-users mailing list >> [email protected] >> https://lists.sourceforge.net/lists/listinfo/geotools-gt2-users >> ------------------------------------------------------------------------------ RSA(R) Conference 2012 Mar 27 - Feb 2 Save $400 by Jan. 27 Register now! http://p.sf.net/sfu/rsa-sfdev2dev2 _______________________________________________ Geotools-gt2-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/geotools-gt2-users
