[DAS2] tiled queries for performance

[Allen Day]

On Mon, 28 Nov 2005, Lincoln Stein wrote:

> One thing to do is to add to the spec a note that the server is free to return 
> features from a range larger than requested. This way the server is free to 
> expand the range to the 1k boundaries.

This would require the returned payload to contain the bounds of the 
features actually returned.  E.g. if client asks for 1500..1600, and 
server responds with 1001..2000, it needs a way to tell the client what 
the actual bounds of the response are.

> 
> My preference, however, would be for the server to implement a filter that 
> removes from the precalculated tiled XML output all features that are outside 
> the range. This would be completely transparent to the client.

Yes, this is what I plan to do if we agree to use one of the tiling
variants.

-Allen

> 
> Lincoln
> 
> On Friday 25 November 2005 06:43 pm, Andrew Dalke wrote:
> > Asim Siddiqui
> >
> > > I think this is a great idea.
> > >
> > > I don't see this as a big change to the DAS/2 spec or requiring much in
> > > the way of additional smarts on the client side.
> >
> > I agree with Allen on this - in some sense there's no effect on the
> > spec.  It ends up being an agreement among the clients to request
> > aligned data, by rounding up/down to the nearest, say, kilobase and
> > for the server implementers to cache those requests.
> >
> > > The change is simply that instead of the client getting exactly what it
> > > asks for, it may get more.
> >
> > While that's another matter - the client makes a request
> > and the server is free to expand the range to something it can handle
> > a bit better.  Allen?  Were you suggesting this instead?
> >
> > In this case there is a change to the spec, and all clients must
> > be able to filter or otherwise ignore extra results.
> >
> > I personally think it's an implementation issue related to performance
> > and there are ways to make the results be generated fast enough.
> >
> > 					Andrew
> > 					dalke at dalkescientific.com
> >
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> 
>