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]
> > (mailto:[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?
> > >
> > >
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>
>
>
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