Berkeley DB Family

I have a query that returns about 10MB worth of data when run against my db -- it looks something like the following

'for $doc in collection("VcObjStore")/doc
where $doc[@type="Foo"]
return <item>{$doc}</item>'

when I run this query in dbxml.exe, I see memory footprint (of dbxml.exe) increase 125MB. Once query finishes, it comes back down.

I expected memory consumption to be somewhat larger than what the query actually returns but this seems quite extreme.

Is this behavior expected? What is a general rule of thumb on memory usage with respect to result size (is it really 10x)? Any way to make it less of a hog?


Thanks