Dear members, dear Christian,
when using a for-loop inside of a for-loop I run into serious
performance-problems, when I'm using variables to return results.
For example this code-line takes 36780ms (!!!) for evaluation:
return <li><a>{$title}</a>{$quote}</li>
When I substitute the variable $time with the defining code, it takes only
711ms for evaluation (!!):
<li><a>
{ if ($ele/ancestor::tei:TEI//tei:titleStmt/tei:title[@type="short"]) then
$ele/ancestor::tei:TEI//tei:titleStmt/tei:title[@type="short"]/string()
else if
($ele/ancestor::tei:TEI//tei:titleStmt/tei:title[@type="article"]) then
$ele/ancestor::tei:TEI//tei:titleStmt/tei:title[@type="article"]/string()
else if ($ele/ancestor::tei:TEI//tei:titleStmt/tei:title[@type="main"])
then $ele/ancestor::tei:TEI//tei:titleStmt/tei:title[@type="main"]/string()
else ()}
</a>{$quote}</li>
The only difference in the code is using a variable and it differs in
performance by a factor of more than 50. In my real application (using more
variables) it differs by factor more than 150.
I tried to simulate the problem with a simple factbook-query. Here is the code:
xquery version "3.0";
let $query := "Pa.*"
for $city in doc('factbook')//city/name
for $hits in ft:mark($city[.//text() contains text {$query} using wildcards])
let $country_of_city := $city/ancestor::country/name
return
(: fast version: Evaluating 12.54ms :)
<hit><city>{$hits}</city><country>{$city/ancestor::country/name}</country></hit>
(: slow version: Evaluating 35.78 :)
(: <hit><city>{$hits}</city><country>{$country_of_city}</country></hit> :)
Also here is a performance bottleneck (not as dramatically: factor 3). Is there
any solution to the problem? Now I'm working in my code without variables in
the result part of the xquery, but it makes realy ugly non maintainable code.
Any help would be appreciated.
- Günter
