Re: xquery nested loops

Hi,

Adam Retter schrieb:

>
> Have you set up appropriate indexes?

Well, I had the fulltext index specified for everything but now added
qnames for Publish and Ordering (see below). There is a small
improvement but still I don't know why such a query should take more
than 1-2 seconds. I have no idea if my xquery is so expensive or what I
should change to not have a near 100% processor load for more than 5-10
seconds...

Thanks, Max

<collection xmlns="http://exist-db.org/collection-config/1.0">
  <index>
      <fulltext default="all" attributes="yes"/>
      <!-- Range indexes -->
      <create qname="@Guid" type="xs:string"/>
      <create qname="@Publish" type="xs:boolean"/>
      <create qname="@Ordering" type="xs:integer"/>
  </index>
</collection>
>
>
> 2008/4/25 Max Gaerber <mgaerber@... <mailto:mgaerber@...>>:

>
>     Hi all,
>
>     I've got a question about performance tuning and nested xquery loops.
>     The data to be queried has several nesting levels, e.g.
>
>     <Publication Guid="a">
>       <CategoryLink Guid="b" Ordering="1" Publish="true">
>          <ProductInfoLink Guid="c" ...>
>              <ProductItemLink Guid="d" ...>
>
>     A Publication has 5-20 Category elements with each about 50
>     ProductInfo
>     elements with each 2-10 ProductItem. Publication is only a "wrapper"
>     declaring some extra information whereas the "real" data of
>     ProductInfo
>     etc. come from another collection.
>
>     There are three functions similar to the one below which loop through
>     the element set and create xhtml for display on a web site. The
>     call to
>     local:ProductInfos($catLink) processes the next nesteing level and so
>     on. Now, the query is quite slow ( > 10 seconds ) even for small
>     Publications. Is there a better way to handle this sort of nesting?
>
>     declare function local:Categories($pub as node()) as node()? {
>        <ul class="categories"> {
>            for $catLink in $pub/CategoryLink
>            let $cat := collection(/Syncrovet/Category)//Category[@Guid =
>     $catLink/@Guid]
>            let $publish := ($catLink/@Publish = "true")
>            order by $catLink/@Ordering
>            return
>            <li class="category {if ($publish) then "included" else
>     "excluded"}" id="{$catLink/@Guid}">
>                <span class="name">{$cat/Name cast as xs:string}</span>
>                { local:Tags($catLink) }
>                { if ($publish) then local:ProductInfos($catLink) else () }
>            </li>
>        }</ul>
>     };
>
>     Thanks,
>
>     Max
>
>
>
>
>
>
>
>
>
>
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> Adam Retter
>
> eXist Developer
> { England }

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