Performance issue related with Casting.

Hi, I am invoking a java method inside My XQuery script, My java methods returns a string array which contains the Id of elements. Now I am taking that list in a xquery variable. It looks like this.

let $ids := javacontext:getIds(); // Java Method
return /sample_xml/category/product[@id = $ids]

Now the problem is that, It is working fine with this, but when I declare variable $ids as xs:string* sequence. It performance is decreased by almost 100%. It looks like this.

let $ids as xs:string* := javacontext:getIds(); // Java Method
return /sample_xml/category/product[@id = $ids]

But, for bigger no of products, and ids . when the variable $ids declared as xs:string*, it is working good, but when I removed xs:string*. it performance decreased drammatically. I have no idea, why it is working in such a way. Any kind of help is appreciated. Thanks, Ankit

Hi Ankit,

The reason is the existence of the Java function: We cannot always determine statically what types the results will have. As a result, we cannot statically detect that $ids will always be a sequence of strings, and as a result, your path expression cannot be rewritten to an index request. Generally, it's always recommendable to explicitly specify type information in your query; it will improve performance in many cases. A reminder: Check out the compilation steps in the info view, they will give you insights how your query will be compiled. Christian It performance is decreased by almost