• From: Michael Kay <mike@s...>
• To: Peter Flynn <peter@s...>
• Date: Wed, 11 Jul 2018 00:03:51 +0100

A decent optimizer will convert count(XXX)=0 to empty(XXX), but you run the risk that without a decent optimizer, the processor will carefully count how many items satisfy the predicate rather than returning a result as soon as it finds the first.

Michael Kay
Saxonica

> On 10 Jul 2018, at 23:06, Peter Flynn <peter@s...> wrote:
> 
> On 10/07/18 22:42, Costello, Roger L. wrote:
>> Hi Folks,
>> 
>> So, you’ve got an XML document containing a bunch of integers:
>> 
>> <Test>
>>     <x>2</x>
>>     <x>4</x>
>>     <x>5</x>
>>     <x>7</x>
>>     <x>10</x>
>>    …
>> </Test>
>> 
>> You want to know: Is it true that not all the integers are even?
> 
> I'd test if count(Test/x[. mod 2 gt 0])=0
> 
> But I don't know if there is a penalty in processing that compared with
> the more complex solutions.
> 
> ///Peter
> -- 
> Peter Flynn | Principal Consultant | Silmaril Consultants | Cork 🇮🇪
> Ireland | ☎ +353 86 824 5333 | ✉ peter@s... | 🌍
> blogs.silmaril.ie/peter
> 
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• Follow-Ups:
  • Re: Duality of quantifiers
    • From: Rick Jelliffe <rjelliffe@a...>

• References:
  • Duality of quantifiers
    • From: "Costello, Roger L." <costello@m...>
  • Re: Duality of quantifiers
    • From: Peter Flynn <peter@s...>