RE: [xsl] Max size?

Subject: RE: [xsl] Max size?
From: "Michael Kay" <michael.h.kay@xxxxxxxxxxxx>
Date: Thu, 9 Jan 2003 13:11:22 -0000
> Edward.Middleton@xxxxxxxxxxx wrote:
> > Do you mean it creates a complete tree for the document before 
> > processing, or just a tree containing the currently 
> processed portion 
> > of the document?
> 
> It depends. AFAIK Saxon always produces a full in-memory 
> representation of the whole document. Xalan is capable of 
> "streaming processing". If told so it may hold only a portion 
> of the processed source in memory. With a generic 
> copy-through style sheet Xalan should be able to work on 
> input of arbitrary size.
> 
> J.Pietschmann

I can't speak with any authority about Xalan, but my understanding is
that it builds the tree concurrently with doing the transformation; by
the time you've finished, you will normally have the complete tree in
memory. This has benefits, but the memory you need still increases
linearly with document size.

The interesting challenge is to work out when you can discard parts of
the tree that won't be needed again. I think this could be done quite
easily for a small class of very simple stylesheets, but the general
problem is quite hard.

Michael Kay


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