Re: [Exist-open] Paging on sorted sequences

[<km...@we...>]

I do not really understand when the results are cached. Do eXist caches t=
he
sorted sequence in the following simple example:

declare function myns:getResults($term) as element()*
{
    for $ch in collection('/db/data')/element/child[starts-with(@att,
$term)]
    let $att :=3D $ch/@att
    order by $att
    return
        <newelement id=3D"{$att}">
			{$ch/title}
		</newelement>
};

let $start :=3D request:get-parameter("start", "1") cast as xs:int,
	$results :=3D myns:getResults('1234')
return
	subsequence($results, $start, 20)


I think not. What di I have to do in order to let eXist cache the results=
?
Sorry for my ignorance...

Kai

> -----Original Message-----
> From: exi...@li...
> [mailto:exi...@li...]On Behalf Of Michael
> Beddow
> Sent: Wednesday, January 17, 2007 10:54 AM
> To: exi...@li...
> Cc: Kai M=FCtz
> Subject: Re: [Exist-open] Paging on sorted sequences
>
>
> Kai M=FCtz wrote:
>
> > is there a best practice to implement paging with XQuery/eXist? I.e. =
is
> > there a possibility to get the first 20 items of a sorted sequence ot=
her
> > than using subsequence or similar expressions on the entire sequence?
> > Performance is very important.
>
> In my experience with this problem, speed of retrieval of a subsequence
> isn't really an issue, especially if the results are cached and then
> retrieved by subsequent operations on the cache (i.e. on an array of
> pointers, not on the data to which they point) each time a new page is
> requested. It's getting the result sequence sorted in the first
> place that's
> so costly, and in many situations that sort has to be performed up fron=
t
> because it's the basis of the page grouping. I have found this a major
> obstacle to using eXist (or any other XQuery implementation I
> have tried) in
> any application where paged presentation of large sorted datasets
> is of the
> essence.
>
> Michael Beddow
>
>
> -----------------------------------------------------------------------=
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