The server takes care of all that, automatically. You can see whether or
not a particular document access was cached by calling
xdmp:query-meters() at the end of your query. Look for
'expanded-tree-cache-hits', which are summarized at the top and also
detailed per-document.
-- Mike
On 2009-08-03 12:45, Runstein, Robert E. (Contr) (IS) wrote:
Thanks for the below suggestion to reduce the number of passes through
the lookup document. Is there a mechanism I can use to cache the lookup
document so that I only need to read the fragment into memory once
rather than for each incoming document that needs to be processed? It
would need to have a way to periodically invalidate the cache since the
lookup document can change.
Bob
Robert,
There's a difference, and I'd expect the expression without the 'where'
to be more efficient. But within a single (unfragmented) doc, it doesn't
matter much because the entire fragment will end up in memory either
way. You could profile the query to see.
But I think there's room for improvement. Here's how I'd write that
query:
doc($lookup-uri)/value-list/values[key = $keys]
First, it's almost always more efficient to specify a complete XPath
than to use '//'. Next, turned the for-expression over $keys into a
simple predicate lookup with multiple values. This works because '=' is
a list-comparison operator, and should result in one pass through the
document rather than N passes.
As Geert mentioned, you might also consider using a map
(http://developer.marklogic.com/pubs/4.1/apidocs/map.html).
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