Re: How to speed up parsing ??

Hi,

Very good job Ashish!

You said "<xsl:value-of>  in preference to <xsl:apply-templates>"

What's about <xsl:copy-of> instead of  <xsl:value-of> ?

Thanks,
Django

----- Original Message ----- 
From: "Tengshe, Ashish" <Tengshe.Ashish@xxxxxxxxxxxxx>
To: <xsl-list@xxxxxxxxxxxxxxxxxxxxxx>
Sent: Thursday, July 31, 2003 12:10 PM
Subject: RE:  How to speed up parsing ??


> Hi,
> Here is a thread that you might want to see
> http://sources.redhat.com/ml/xsl-list/2001-02/msg01730.html click on
'Thread Index' to see all responses.
> The general consensus from the Gurus seem to be that for-each is not
slower than apply-templates, just one needs to find out when it is
appropriate to use.
> One post even quotes the Apache website as saying "for-each is faster
because there is no template matching involved". I think you may need to
look in other places to increase performance.
>
> This may not be relevant to you but I thought I'd just post these
performance tips, you can see if any apply to you
> These are from noted author Michael Kay and other sources
>
> 1. Avoid repeated use of "//item". This is very expensive. Use an Xpath
expression that's as close to the exact one (that can identify the wanted
nodes) as possible.
> 2. Don't evaluate the same node-set more than once, save it in a variable.
> 3. Avoid <xsl:number> if you can. For example, by using position()
function.
> 4. Use <xsl:key>, for example to solve grouping problems. There is an
example of this in this document.
> 5. Avoid complex patterns in template rules. Instead, use <xsl:choose>
within the rule.
> 6. Be careful when using the preceding[-sibling] or following[-sibling]
axes. This often
>         indicates an algorithm with n-squared performance.
> 7. Don't sort the same node-set more than once. If necessary, save it as a
result tree fragment
>        and access it using the node-set() extension function.
> 8. To output the text value of a simple #PCDATA element, use
<xsl:value-of>
>         in preference to <xsl:apply-templates>.
> More...
> 1. Keep the source documents small. If necessary split the document first.
> 2. Keep the XSLT processor (and Java VM) loaded in memory between runs
> 3. If you use the same stylesheet repeatedly, compile it first.
> 4. If you use the same source document repeatedly, keep it in memory.
> 5. If you perform the same transformation repeatedly, don't. Store the
result instead.
> 6. Keep the output document small. For example, if you're generating HTML,
use CSS.
> 7. Never validate the same source document more than once.
> 8. Split complex transformations into several stages.
>
> More...
> · Follow good performance engineering practice: record the time a
stylesheet takes before and after making each change, and change it back if
it doesn't improve
> · Use small documents rather than large ones
> · Don't assume that the processor makes a particular optimization
> · Use variables for storing Xpath results, do not access same nodes again.
> · Use temporary trees (result tree fragments in XSLT 1.0)
> · A 10% improvement is considered industry benchmark to justify a
substantial change.
>
> More...from the Apache Website
> · Avoid using predicates in '*' patterns
> · Avoid using id/key-patterns
> · Avoid union expressions where possible
> · Sort stored node-sets once
> · Cache input documents
>
> Lastly,
> · Follow Design Patterns!
>
> Also, probably not logical at all, but I read on one forum that if this
guy used  <xsl:apply-templates select="*"/> instead of
<xsl:apply-templates/> the performance increased drastically. Just something
to try.
>
> Thanks,
> Ashish
>
>
>
> -----Original Message-----
> From: owner-xsl-list@xxxxxxxxxxxxxxxxxxxxxx
> [mailto:owner-xsl-list@xxxxxxxxxxxxxxxxxxxxxx]On Behalf Of Dipesh
> Khakhkhar
> Sent: Wednesday, July 30, 2003 6:16 PM
> To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
> Subject:  How to speed up parsing ??
>
>
> Hi,
>
> I would like to know how can i speed up parsing xml file.
> I am having huge xml file (approx 30-50 MB). I have written xsl to get
text
> out it. I am getting it properly but it is taking lotta time.
>
> I have used "apply templates " frequently to go to the respective node. As
per
> my knowledge "for-each" and "apply-templates" does the same thing and i
assume
> internally they must be working alike. WILL THERE BE SPEED ENHANCEMENT IF
I
> USE FOR-EACH INSTEAD OF USING APPLY_TEMPLATES.
>
> Or if you do programatically the same thing will i be achieving speed
> enhancement ??
>
> My current xsl is drastically slow. Pls give me some hints and suggestion
to
> enhance performance of my xsl processing.
>
> Eagerly waiting for reply.
>
> Regards,
> Dipesh
>
>
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>
>
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>


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