XSLT 使用 concat 或多个 value-of 元素连接变量？

Question

Assume I have like 20 variables that I want to join to a csv string. Should I prefer concat() , or just place all variables below each other in <xsl> elements?

either:

<xsl:value-of select="concat($var1, ';', ..., $var10)"/>

or:

<xsl:value-of select="$var1"/>
<xsl:text>;</xsl:text>
...
<xsl:value-of select="$var10"/>

Especially regarding to performance, as I have hundred million rows to process.

Is the contact approach similar to a java StringBuilder , and the element approach similar to a string += val reassignment? If the, the concat would of course be superior. But is that true?

Answer 1

It's very unlikely there will be a measurable performance difference, but the only way to find out is to measure it.

In Saxon a concat() call will always build the string in memory (until the next Saxon release...) while a series of xsl:text / xsl:value-of calls will (where possible) write it incrementally to the serializer, so that might make a difference to memory usage if the string is extremely large.

Answer 2

At least I found out by profiling that contact() performed 25% better than multiple xsl:text/xsl:value-of calls. But I don't know if that can be said in general, but in my case with hundred millions of rows that's it.