[xquery-talk] From map entry pairs to a pair of arrays

Michael Kay mike at saxonica.com
Sun Jul 16 14:58:11 PDT 2017

ce between C and Assembly is a lot smaller than between C and XQ, and I think memory management should not be taken lightly (I'm not saying you do). In OP's case, I believe keys could be discarded while memory layout remains intact.

As a general rule of thumb, a lower-level language performs better provided that you have the time and skills to write the code efficiently.

And as a general rule of thumb, you don't. 

Even when you are quite convinced that you do.

It's a long time since I wrote in anything as low-level as C or assembler, but if you compare XQuery and Java, the level of abstraction of the API for maps is very similar, so there is no intrinsic reason to believe one should perform better than the other. The main difference is that maps in XQuery are immutable, which means you pay a little more for some operations (like adding a new entry), and you pay a lot less for other operations (llike bulk copying).

Michael Kay

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