XQuery variable declaration (again :-)

[Marko Bozikovic-2]

Hi all,

I haven't received any answers to my previous mail, and reading it I realized
the question might not have been completely clear. I will try again :-)

This is a test query that I have:

declare function local:foo($year as xs:string) as xs:string
{
 (: do something :)
};

declare variable $year := '2005';

<foo>
{
let $u := local:foo($year)
return $u
}
</foo>

This query executes in about half a second (function foo performs a query from
a database)


However, I need a 'global' variable, so I changed the query to:

declare function local:foo($year as xs:string) as xs:string
{
 (: do something :)
};

declare variable $year := '2005';
declare variable $u := local:foo($year);

<foo>
{$u}
</foo>

This query takes 7-8 seconds to execute.

Any ideas why? Current query use our project database, but maybe I can create
a minimal example that reproduces the problem is needed.

TIA,
--
Marko Božiković
Tellus d.o.o.
Tel.  [phone]
Fax   [phone]
E-Mail:  marko.bozikovic@...
Ogrizovićeva 40a
10000 Zagreb
Hrvatska


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[John Snelson-4]

Hi Marko,

The statistics you quote are very strange, and I will certainly be
looking into why that might be the case. In the mean time, maybe you
could try a query like this, and let me know how it performs:

declare function local:foo($year as xs:string) as xs:string
{
  (: do something  :)
};

declare variable $year := '2005';

let $u := local:foo($year)
return

<foo>
{$u}
</foo>

John

Marko Bozikovic wrote:

> Hi all,
>
> I haven't received any answers to my previous mail, and reading it I realized
> the question might not have been completely clear. I will try again :-)
>
> This is a test query that I have:
>
> declare function local:foo($year as xs:string) as xs:string
> {
>  (: do something :)
> };
>
> declare variable $year := '2005';
>
> <foo>
> {
> let $u := local:foo($year)
> return $u
> }
> </foo>
>
> This query executes in about half a second (function foo performs a query from
> a database)
>
>
> However, I need a 'global' variable, so I changed the query to:
>
> declare function local:foo($year as xs:string) as xs:string
> {
>  (: do something :)
> };
>
> declare variable $year := '2005';
> declare variable $u := local:foo($year);
>
> <foo>
> {$u}
> </foo>
>
> This query takes 7-8 seconds to execute.
>
> Any ideas why? Current query use our project database, but maybe I can create
> a minimal example that reproduces the problem is needed.
>
> TIA,

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[Marko Bozikovic-2]

John Snelson wrote:

> Hi Marko,
>
> The statistics you quote are very strange, and I will certainly be
> looking into why that might be the case. In the mean time, maybe you
> could try a query like this, and let me know how it performs:
>
> declare function local:foo($year as xs:string) as xs:string
> {
>  (: do something  :)
> };
>
> declare variable $year := '2005';
>
> let $u := local:foo($year)
> return
>
> <foo>
> {$u}
> </foo>

Thanks, this works faster :)

Here's a test setup that reproduces the problem:

Create XML files:

<foo id="U-XXX-YY-ZZ" year="20YY">
    <data>foo</data>
</foo>

Filename format is U-XXX-YY-ZZ.xml. XXX is 0-499, YY is 04-06 and YY is 01-03 (this
gives 4500 files).

Create a test container (default: indexed nodes). Create indexes for id and year
attributes, both node-attribute-equality-string. Import XML files.

This is the query:

declare function local:foo($year as xs:string) as xs:string*
{
   for $i in
      distinct-values(
         collection('test.dbxml')
            /*[starts-with(@id, 'U-') and (@year = $year)]
               /substring(string(@id), 3, 3)
      )

      return collection('test.dbxml')
               /*[@id =
                  string(
                     max(
                        collection('test.dbxml')
                           /*[starts-with(@id, concat('U-', $i, '-', substring($year, 3, 2)))]
                              /string(@id)
                     )
                  )
                 ]
               /string(@id)
};


declare variable $a := local:foo($year);

<doc name='Foo' year='{substring($year, 3, 2)}'>
{
$a
}
</doc>

This query takes approx. 17 seconds (and yes, I struggle a bit with XQuery
formatting :-)

Changing the last part to:

<doc name='Foo' year='{substring($year, 3, 2)}'>
{
let $a := local:foo($year)
return $a
}
</doc>

This query takes approx. 2 seconds to complete.


Another interesting thing is that using computed contructor text in the
first example improves speed:

declare variable $a := text{local:foo($year)};

<doc name='Foo' year='{substring($year, 3, 2)}'>
{
$a
}
</doc>

This query also takes approx. 2 seconds to complete.

Thank you,
--
Marko Božiković
Tellus d.o.o.
Tel.  [phone]
Fax   [phone]
E-Mail:  marko.bozikovic@...
Ogrizovićeva 40a
10000 Zagreb
Hrvatska


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