Re: [xsl] Which is faster: count(/Document/A/B) eq 1 ... or ... /Document/A/(count(B) eq 1) ?

Subject: Re: [xsl] Which is faster: count(/Document/A/B) eq 1 ... or ... /Document/A/(count(B) eq 1) ?
From: Dimitre Novatchev <dnovatchev@xxxxxxxxx>
Date: Wed, 19 Sep 2012 07:25:57 -0700
> /*/*/b[1][not(following-sibling::b)]


Of course, I meant:

  /*/*/B[1][not(following-sibling::B)]



On Wed, Sep 19, 2012 at 7:24 AM, Dimitre Novatchev <dnovatchev@xxxxxxxxx> wrote:
> /*/*/b[1][not(following-sibling::b)]
>
> Cheers,
> Dimitre
>
> On Wed, Sep 19, 2012 at 7:07 AM, David Carlisle <davidc@xxxxxxxxx> wrote:
>> On 19/09/2012 14:34, Costello, Roger L. wrote:
>>>
>>> Is there an XPath expression, besides the ones listed, that is even better
>>> and faster?
>>
>>
>>
>> You want to avoid count() as then you are relying on the optimiser to
>> rewrite it away. If you go count(B) eq 1 then unless the optimiser spots
>> this it may try to calculate count(B) which would mean processing the full
>> list of elements.
>>
>> B and not(B[2])
>>
>> similarly may be read as evaluating the full list of B elements and then
>> taking the 2nd but it is much more likely the optimiser detects [2]
>> predicates to abort the construction of the sequence at the second item.
>>
>> David
>>
>>
>> --
>> google plus: https:/profiles.google.com/d.p.carlisle
>>
>> ________________________________________________________________________
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>
>
>
> --
> Cheers,
> Dimitre Novatchev
> ---------------------------------------
> Truly great madness cannot be achieved without significant intelligence.
> ---------------------------------------
> To invent, you need a good imagination and a pile of junk
> -------------------------------------
> Never fight an inanimate object
> -------------------------------------
> To avoid situations in which you might make mistakes may be the
> biggest mistake of all
> ------------------------------------
> Quality means doing it right when no one is looking.
> -------------------------------------
> You've achieved success in your field when you don't know whether what
> you're doing is work or play
> -------------------------------------
> Facts do not cease to exist because they are ignored.
> -------------------------------------
> Typing monkeys will write all Shakespeare's works in 200yrs.Will they
> write all patents, too? :)
> -------------------------------------
> I finally figured out the only reason to be alive is to enjoy it.



-- 
Cheers,
Dimitre Novatchev
---------------------------------------
Truly great madness cannot be achieved without significant intelligence.
---------------------------------------
To invent, you need a good imagination and a pile of junk
-------------------------------------
Never fight an inanimate object
-------------------------------------
To avoid situations in which you might make mistakes may be the
biggest mistake of all
------------------------------------
Quality means doing it right when no one is looking.
-------------------------------------
You've achieved success in your field when you don't know whether what
you're doing is work or play
-------------------------------------
Facts do not cease to exist because they are ignored.
-------------------------------------
Typing monkeys will write all Shakespeare's works in 200yrs.Will they
write all patents, too? :)
-------------------------------------
I finally figured out the only reason to be alive is to enjoy it.

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