> Is there a way to skip a portion of the dom tree during an xpath 
traversal? 

Yes, you can provide a particular context node, so the search starts from 
that point.

> [I can also change the xalan source code and submit a patch for this 
functionality.] 

Well, more detail about what you're trying to do would be the best place 
to start.

> The dom tree that i am traversing is pretty big but one subtree is very 
expensive to
> traverse due to its size. The xpath queries don't normally require me to 
 traverse that
> subtree so i want to skip it for normal xpath traversals.

Well, why don't you write your query to skip that particular subtrees?

> The problem comes with // expressions or following:: or preceding:: 
expressions. the
> xpath engine  starts traversing the whole dom tree and the efficiency is 
significantly reduced.

Using // or the following and preceeding axes will always be expensive in 
large tree.  Can you re-write your XPath expressions to narrow down what 
you really want to look at?

> Can i put some restriction in the xpath engine for this? 

No.  If you don't want to search a large tree, write your XPath 
expressions in such a way that you're not searching the entire tree, or 
don't build the subtrees you're not interested in.

Your description is so abstract it's difficult to offer any advice.  A few 
concrete examples of the XPath expressions that are problematic might help 
us understand what you're trying to do.

Dave

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