This sort of thing is very dependent on the product you are using. My first
guess is that the version that uses a union operation is more likely to
require a sort, and therefore likely to be slower. On the other hand, it may
avoid searching large parts of the subtree underneath $source - I don't
know. You really can't tell without making measurements.

Michael Kay

> -----Original Message-----
> From: Bruce D'Arcus [mailto:bdarcus@xxxxxxxxxxxxx] 
> Sent: 16 September 2004 22:23
> To: XSL-List@xxxxxxxxxxxxxxxxxxxxxx
> Subject:  performance issues and selecting
> 
> As a general rule, what is likely to be the performance difference 
> between this:
> 
> <xsl:template match="cs:place">
>    <xsl:param name="source"/>
>    <xsl:apply-templates select="$source/mods:originInfo/mods:place |
> 			      
> $source/mods:relatedItem/mods:originInfo/mods:place">
>      <xsl:with-param name="prefix" select="@before"/>
>      <xsl:with-param name="suffix" select="@after"/>
>    </xsl:apply-templates>
> </xsl:template>
> 
> .... and this:
> 
> <xsl:template match="cs:place">
>    <xsl:param name="source"/>
>    <xsl:apply-templates select="$source/descendant::mods:place">
>      <xsl:with-param name="prefix" select="@before"/>
>      <xsl:with-param name="suffix" select="@after"/>
>    </xsl:apply-templates>
> </xsl:template>
> 
> .... and splitting these into two separate templates each with a more 
> specific match?  I notice my stylesheet has slowed down a 
> bit, and want 
> to understand the performance implications of what I'm doing before I 
> go farther.
> 
> Bruce