Hi Kelly,
Would you elaborate on the new functionality of 4.2 to which you are referring? I'm using a CPF to effectively spawn tasks on individual documents extracted from a zipfile, but the problem is that I can't conveniently capture all the statuses of the spawned tasks and provide a single email that collects and reports on all the statuses. In addition there seems to be no way to report to the parent when all the spawned tasks have completed. I could periodically poll for all the spawned tasks to complete, but that gets kind of messy. Thank you! Tim Meagher -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Kelly Stirman Sent: Wednesday, April 07, 2010 9:51 AM To: [email protected] Subject: [MarkLogic Dev General] RE: tail-recursion with xdmp:spawn Hi Mike, Yes, that's a good approach overall for one-off processing. It doesn't provide the robustness of CPF, but it can be easier to set up. It allows for a multi-threaded approach to processing your documents by configuring the number of threads on the task server. Your termination condition could use properties. When you have completed an update on a document, add a property flag. Then your processing can look for documents that do not have the property in place. /foo[not(property::bar)] is fast /foo[not(property::bar = "baz")] is also fast. cts:property-query() Hope this helps. Also, I think there is new functionality coming in 4.2 that you will appreciate. :-) Hope to see you at the user conference. Kelly Message: 4 Date: Wed, 07 Apr 2010 09:26:06 -0400 From: Mike Sokolov <[email protected]> Subject: [MarkLogic Dev General] tail-recursion with xdmp:spawn To: General Mark Logic Developer Discussion <[email protected]> Message-ID: <[email protected]> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Perhaps this won't be news to others on the list, but I was so excited to finally stumble on a solution to a problem I have been struggling with for years, that I just had to share. The problem: how to process a large number of documents using xquery only? This can't be done easily because if all the work is done in a single transaction, it eventually runs out of time and space. But xquery modules don't provide an obvious mechanism for flow control across multiple transactions. In the past I've done this by writing an "outer loop" in Java, and more recently I tried using CPF. The problem with Java is that it's cumbersome to set up and requires some configuration to link it to a database. I had some success with CPF, but I found it to be somewhat inflexible since it requires a database insert or update to trigger processing. It also requires a bit of configuration to get going. Often I find I just want to run through a set of existing documents and patch them up in some way or another, (usually to clean up some earlier mistake!) Finally I hit on the solution: I wrote a simple script that fetches a batch of documents to be updated, processes the updates, and then, using a new statement after ";" to separate multiple transactions, re-spawns the same script if there is more work to be done after logging some indication of progress. Presto - an iterative processor. This technique is a little sensitive to running away into an infinite loop if you're not careful about the termination condition, but it has many advantages over the other methods. What do you think? Michael Sokolov Engineering Director www.ifactory.com @iFactoryBoston PubFactory: the revolutionary e-publishing platform from iFactory ------------------------------ _______________________________________________ General mailing list [email protected] http://xqzone.com/mailman/listinfo/general
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