[MarkLogic Dev General] results returning faster when using string instead of integer in predicate

[semerau at hotmail.com]

Ok that makes sense.

Also, slightly different, but interesting to me, is the speed results from compound predicates:


/image[sizes[size/@w = "98"]]

~ PT0.016S


/image[sizes[size[@w = "98"]]]

~ PT0.031S


Either having a third level compound predicate or having an attribute as the first step in the predicate makes the difference in this case. Not sure which.


> From: mike at blakeley.com
> Date: Thu, 20 Oct 2011 10:27:40 -0700
> To: general at developer.marklogic.com
> Subject: Re: [MarkLogic Dev General] results returning faster when using	string instead of integer in predicate
> 
> Consider this:
> 
>   attribute w { 123.0 } = 123
>   => true
> 
> If the RHS 123 were converted to string, this would return false because "123.0" != "123". So 123 isn't being converted to string. Rather, every @w must atomize to a numeric type. That seems to be a little more expensive than atomization to string.
> 
> -- Mike
> 
> On 20 Oct 2011, at 10:21 , semerau at hotmail.com wrote:
> 
> > Given a few thousand XML files in the DB that look like this:
> > 
> > <thing>
> >   <sizes>
> >     <size w="123"/>
> >     <size w="456"/>
> >    </sizes>
> > </thing>
> > 
> > with no schema being used, I get different speed results depending on whether I use a string or integer value in the predicate:
> > 
> > /thing[sizes/size/@w = 123]
> > 
> > ~ PT0.031S (average)
> > 
> > 
> > /thing[sizes/size/@w = "123"]
> > 
> > ~ PT0.016S (average)
> > 
> > 
> > Is this because the values in the XML file are stored are a string (codepoint values) and when the predicate uses an integer it must be converted into a string? Or is there something else going on?
> > 
> > thanks,
> > Ryan 
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