I think the other developers need to understand that the cost of supporting
per-feature modified status will be a per-feature cost of (size of int) *
number of attributes. I'm not sure I made that clear. Currently the memory
cost is for all features on all layers. Perhaps there is needed a way to
opt-in to this cost and functionality at layer creation time. Hmm...
Larry
On Thu, Apr 23, 2009 at 4:53 PM, Martin Davis <mbda...@refractions.net>wrote:
> I guess the memory issue might be moot for DataStore-based datasets
> anyway, since the whole point is to only keep in memory what is
> currently displayed on the screen.
>
> But simpler is always better! Alarm bells start ringing for me when I
> see counts being used - the semantics seems like they must be more
> complicated than a simple flag.
>
> Larry Becker wrote:
> > I agree that a mechanism to reset the modified status is needed,
> > especially after the changes to the layer have been flushed to the
> > database. I'll add this to BasicFeature.
> >
> > Your comment about carrying around state data after it is needed is
> > reasonable. The code could check for modified on-the-fly while it is
> > incrementing the attribute mod count and if it is greater than one,
> > set a boolean instead and dispose of the array of ints. You would
> > lose the ability to determine individual attribute mods (not sure if
> > it is needed), however you would only save memory in modified records
> > which wouldn't usually be very much.
> >
> > I was hoping someone would come up with a clever hack that wouldn't
> > require the int array. All of the optimizations that I have
> > considered break in one case or another.
> >
> > BTW, if you really want to save memory on attribute storage, I have a
> > number of questionable schemes that load attributes on an as-needed
> > basis. :-) SkyJUMP even has an optimization were layers that aren't
> > visible are not loaded into memory until you make them visible,
> > although it doesn't go as far as removing them when you make them
> > invisible. Of course the most famous attribute memory-saving scheme
> > is Michael's permgen attribute string scheme for dbf files. That one
> > saves a ton of memory on typically redundant data, until you run out
> > of permgen memory.
> >
> > Larry
> >
> > On Thu, Apr 23, 2009 at 4:06 PM, Martin Davis <mbda...@refractions.net
> > <mailto:mbda...@refractions.net>> wrote:
> >
> > re Mutating Geometry in-place - JTS discourages this, but does not
> > prevent it. Sometimes people do this when they are transforming
> > coordinates (eg. translation or affine transform).. It's quite
> > possible that all the JUMP code is clean, however. In any case, this
> > will only be an issue if that particular function is used.
> >
> > re tracking modifications - how about providing a method that lets
> you
> > clear the modified flag? Then the feature can be constructed as
> > necessary and then marked as clean.
> >
> > It seems heavyweight to carry around a set of data which is only
> > really
> > of use during the construction phase of a Feature. To avoid this,
> I'd
> > even suggest constructing a Feature as needed, then creating a new
> > Feature from it via a constructor which sets the modified flag
> > appropriately. Anything to avoid requiring more storage.
> >
> > How does GeoTools handle this?
> >
> > Larry Becker wrote:
> > > The tricky thing about modifications is not to find a record is
> > > modified just because you set the initial value. It is only
> > modified
> > > if you set it more than once, otherwise all records would be set as
> > > modified as soon as they are loaded.
> > >
> > > The next trick is to consider that you call setAttribute multiple
> > > times with different attribute indexes, so it is necessary to track
> > > the changes to each one separately.
> > >
> > > Mutating Geometries in place is a concern. I have never seen code
> > > that does this, and certainly none of the edit tools or any plugins
> > > that use transactions do this, but it may be possible. Could
> > you just
> > > modify the Coordinate.x and y values? I'll try to construct a
> > > Beanshell test for this, but I doubt that this is a serious
> concern.
> > > All of the tools and plugins that I have tried so far play by
> > the rules.
> > >
> > > Larry
> > >
> > > On Thu, Apr 23, 2009 at 2:12 PM, Martin Davis
> > <mbda...@refractions.net <mailto:mbda...@refractions.net>
> > > <mailto:mbda...@refractions.net
> > <mailto:mbda...@refractions.net>>> wrote:
> > >
> > > Larry, why do you use an int rather than a boolean to flag
> > changed
> > > attributes?
> > >
> > > BTW, In order to track changes to Geometry attributes
> > correctly, the
> > > JUMP codebase needs to be scrutinized to make sure it isn't
> > mutating
> > > Geometries "in place".
> > >
> > >
> > >
> > > Larry Becker wrote:
> > > > Hi,
> > > >
> > > > As I mentioned in the other thread, before the problem
> > of partial
> > > > database updates can be solved, we must first be able to
> > > determine if
> > > > a Feature has been modified. This is not currently
> > possible in
> > > all of
> > > > the JUMP variants that I am familiar with, although Kosmo
> > may have
> > > > implemented it.
> > > >
> > > > The simplest way of implementing it that I can see is to
> > modify
> > > > BasicFeature to include:
> > > >
> > > > private int[] attributeModCount; //this is a parallel
> > array to
> > > > Object[] attributes
> > > >
> > > > Then it would be necessary to allocate the
> > attributeModCount array
> > > > when setAttributes(Object[] attributes) is called.
> > > >
> > > > In addition each time setAttribute(int attributeIndex, Object
> > > > newAttribute) is called, add the line of code:
> > > >
> > > > attributeModCount[attributeIndex]++
> > > >
> > > > With these modifications we could then define:
> > > >
> > > > public boolean isFeatureModified() {
> > > > for (int i=0; i<attributeModCount.length; i++) {
> > > > if (attributeModCount[i] > 1) //modified is defined as
> > > setting
> > > > an attribute more than once
> > > > return true;
> > > > }
> > > > return false;
> > > > }
> > > >
> > > > Would this work and does this seem like something we should
> > > consider?
> > > >
> > > > regards,
> > > > Larry
> > > > --
> > > > http://amusingprogrammer.blogspot.com/
> > > >
> > >
> >
> ------------------------------------------------------------------------
> > > >
> > > >
> > >
> >
> ------------------------------------------------------------------------------
> > > >
> > > >
> > >
> >
> ------------------------------------------------------------------------
> > > >
> > > > _______________________________________________
> > > > Jump-pilot-devel mailing list
> > > > Jump-pilot-devel@lists.sourceforge.net
> > <mailto:Jump-pilot-devel@lists.sourceforge.net>
> > > <mailto:Jump-pilot-devel@lists.sourceforge.net
> > <mailto:Jump-pilot-devel@lists.sourceforge.net>>
> > > >
> https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel
> > > >
> > >
> > > --
> > > Martin Davis
> > > Senior Technical Architect
> > > Refractions Research, Inc.
> > > (250) 383-3022
> > >
> > >
> > >
> >
> ------------------------------------------------------------------------------
> > > Crystal Reports - New Free Runtime and 30 Day Trial
> > > Check out the new simplified licensign option that enables
> > unlimited
> > > royalty-free distribution of the report engine for
> > externally
> > > facing
> > > server and web deployment.
> > > http://p.sf.net/sfu/businessobjects
> > > _______________________________________________
> > > Jump-pilot-devel mailing list
> > > Jump-pilot-devel@lists.sourceforge.net
> > <mailto:Jump-pilot-devel@lists.sourceforge.net>
> > > <mailto:Jump-pilot-devel@lists.sourceforge.net
> > <mailto:Jump-pilot-devel@lists.sourceforge.net>>
> > > https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel
> > >
> > >
> > >
> > >
> > > --
> > > http://amusingprogrammer.blogspot.com/
> > >
> >
> ------------------------------------------------------------------------
> > >
> > >
> >
> ------------------------------------------------------------------------------
> > > Crystal Reports - New Free Runtime and 30 Day Trial
> > > Check out the new simplified licensign option that enables
> unlimited
> > > royalty-free distribution of the report engine for
> > externally facing
> > > server and web deployment.
> > > http://p.sf.net/sfu/businessobjects
> > >
> >
> ------------------------------------------------------------------------
> > >
> > > _______________________________________________
> > > Jump-pilot-devel mailing list
> > > Jump-pilot-devel@lists.sourceforge.net
> > <mailto:Jump-pilot-devel@lists.sourceforge.net>
> > > https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel
> > >
> >
> > --
> > Martin Davis
> > Senior Technical Architect
> > Refractions Research, Inc.
> > (250) 383-3022
> >
> >
> >
> ------------------------------------------------------------------------------
> > Crystal Reports - New Free Runtime and 30 Day Trial
> > Check out the new simplified licensign option that enables unlimited
> > royalty-free distribution of the report engine for externally
> > facing
> > server and web deployment.
> > http://p.sf.net/sfu/businessobjects
> > _______________________________________________
> > Jump-pilot-devel mailing list
> > Jump-pilot-devel@lists.sourceforge.net
> > <mailto:Jump-pilot-devel@lists.sourceforge.net>
> > https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel
> >
> >
> >
> >
> > --
> > http://amusingprogrammer.blogspot.com/
> > ------------------------------------------------------------------------
> >
> >
> ------------------------------------------------------------------------------
> > Crystal Reports - New Free Runtime and 30 Day Trial
> > Check out the new simplified licensign option that enables unlimited
> > royalty-free distribution of the report engine for externally facing
> > server and web deployment.
> > http://p.sf.net/sfu/businessobjects
> > ------------------------------------------------------------------------
> >
> > _______________________________________________
> > Jump-pilot-devel mailing list
> > Jump-pilot-devel@lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel
> >
>
> --
> Martin Davis
> Senior Technical Architect
> Refractions Research, Inc.
> (250) 383-3022
>
>
>
> ------------------------------------------------------------------------------
> Crystal Reports - New Free Runtime and 30 Day Trial
> Check out the new simplified licensign option that enables unlimited
> royalty-free distribution of the report engine for externally facing
> server and web deployment.
> http://p.sf.net/sfu/businessobjects
> _______________________________________________
> Jump-pilot-devel mailing list
> Jump-pilot-devel@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel
>
--
http://amusingprogrammer.blogspot.com/
------------------------------------------------------------------------------
Crystal Reports - New Free Runtime and 30 Day Trial
Check out the new simplified licensign option that enables unlimited
royalty-free distribution of the report engine for externally facing
server and web deployment.
http://p.sf.net/sfu/businessobjects
_______________________________________________
Jump-pilot-devel mailing list
Jump-pilot-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel
