Hello,
we are experiencing a weird performance issue in function calling.
In many xqueries we use, we found that calling functions slows down the execution, sometimes it even hangs "forever".
I tried to drill down to the problem and I think I isolated an odd behavior.
Before presenting the example code, let me summarize a little bit:
inside a for-loop we call a thousand times a function passing some parameters.
I declared 3 functions, 2 of which take 1 parameter and the last one takes 2 parameters.
For simplicity's sake the parameter "objectId" is never used, but that doesn't affect the experiment.
When I call any of the 1-parameter functions, execution takes less than 2 seconds, but when I call the 2-parameter function it runs endlessly.
It seems that the combination of those two parameters is the point of performance issue.
I hope you can illuminate me.
Regards
William
 
Here it is an example:

declare namespace xbpr = "http://www.bpeng.com/";

declare variable $amlDocName as xs:string :="aml";
declare variable $cxnDefsDocName as xs:string :="cxnDefsDocName";

declare function xbpr:testFast1($objectId as xs:string?){
let $docName := $cxnDefsDocName
let $conn_typeof_target := doc($docName)/CxnDefs/CxnDef[@type="RdfsType"]/@target
return $conn_typeof_target    
};

declare function xbpr:testFast2($docName as xs:string?){
let $conn_typeof_target := doc($docName)/CxnDefs/CxnDef[@type="RdfsType"]/@target
return $conn_typeof_target    
};

declare function xbpr:testSlow($docName as xs:string?, $objectId as xs:string?){
let $conn_typeof_target := doc($docName)/CxnDefs/CxnDef[@type="RdfsType"]/@target
return $conn_typeof_target    
};

let $instances := doc($amlDocName)/AML/Group//ObjDef   
for $instance in $instances
    let $objectId := $instance/@ObjDef.ID
    let $v := xbpr:testFast1($objectId) 
    let $v := xbpr:testFast2($cxnDefsDocName)
    let $v := xbpr:testSlow($cxnDefsDocName, $objectId)
  return $v