Yes, makes sense. Basically we'd return a new sequence object backed by the
same set of items, right?
I also realized now, why running times are ok for me: I get an OutOfMemoryError
on that query ...
How big is your heap when you run the suite?
Till
On Jan 5, 2010, at 1:24 AM, Vinayak Borkar wrote:
> In this specific case, the sequence is materialized anyways since its
> assigned to a global variable and then used in a loop. If we add a
> subsequence() method on XDMSequenece, that creates the subsequence in
> constant time.
>
> The compiler could replace the subsequence function with the
> subsequence-of-materialized-sequence function when it notices the
> materialization condition.
>
> Vinayak
>
> Till Westmann wrote:
>> How would you optimize this?
>> Materialize the sequence and index it?
>> Or evaluate multiple expressions on the sequence during one scan?
>> Or ...?
>> Till
>> On Jan 5, 2010, at 12:55 AM, Till Westmann wrote:
>>> Hmm, is this test part of a later revision of the test suite? For me test
>>> execution never was a real problem ...
>>>
>>> How slow is it?
>>>
>>> Thanks,
>>> Till
>>>
>>> On Jan 4, 2010, at 9:50 PM, Vinayak Borkar wrote:
>>>
>>>> Its not an infinite loop --
>>>> Expressions/Construct/DirectConElem/DirectConElemContent//Constr-cont-document-3.xq
>>>>
>>>> is taking a long time to run. I am pasting the query below.
>>>>
>>>> The query iterates over about 1.1 M integers 70 at a time and calls
>>>> subsequence() for the 70 items in the window. This is a quadratic
>>>> operation in the engine -- and takes a long time.
>>>>
>>>> Should we optimize this case?
>>>>
>>>>
>>>> Thanks,
>>>> Vinayak
>>>>
>>>>
>>>> --- Query begin ---
>>>>
>>>>
>>>> declare variable $codepoints as xs:integer+ := (9, (: 0x9 :)
>>>> 10,(: 0xA :)
>>>> 13,(: 0xD :)
>>>> 32 to 55295, (: 0x20 - 0xD7FF
>>>> :)
>>>> 57344 to 65532, (: 0xE000 -
>>>> 0xFFFD :)
>>>> 65536 to 1114111 (: 0x10000 -
>>>> 0x10FFFF :));
>>>> declare variable $count as xs:integer := count($codepoints);
>>>> declare variable $lineWidth as xs:integer := 70;
>>>>
>>>> <allCodepoints>
>>>> <!-- Each <r>-element represents a codepoint range. The 's' attribute
>>>> is the start codepoint, the 'e' attribute is the end codepoint.
>>>> Note that these are only *Hints*, since the character range is not
>>>> contiguous.
>>>> -->
>>>> {
>>>> "
",
>>>> "
",
>>>> (: The outputted file is rather big, so to make it managable, we output
>>>> a chunk of $lineWidth characters in each element.
>>>> :)
>>>> for $i in (1 to $count idiv $lineWidth)
>>>> let $startOffset := (($i - 1) * $lineWidth) + 1
>>>> return (<r s="{$codepoints[$startOffset]}"
>>>> e="{$codepoints[$startOffset] + $lineWidth}">
>>>> {
>>>> codepoints-to-string(subsequence($codepoints,
>>>> $startOffset, $lineWidth))
>>>> }
>>>> </r>, "
")
>>>> }
>>>> </allCodepoints>
>>>>
>>>> --- Query end ---
>>>>
>>>> Vinayak Borkar wrote:
>>>>> Till,
>>>>> Does XTest on the test suite terminate? Some query is throwing the engine
>>>>> into an infinite loop. Do you see this?
>>>>> Thanks,
>>>>> Vinayak
