BaseX-Talk January 2010

basex-talk@mailman.uni-konstanz.de

14 participants
24 discussions

Issues with XQuery insert
by j.gager＠metadatatechnology.com 27 Jan '10

27 Jan '10

Hello We are using BaseX6 to manage a local repository of XML artifacts in a Java based application. We initially start with an empty collection, and add documents as they are needed. We have tried a number of approaches to this (more to come on this in a separate email). One such approach is to insert the documents as nodes into the container using XQuery. Example: insert nodes document {<t:test xmlns:t='xyz' xmlns:s='def'>good <s:test>bye</s:test></t:test>} into collection('MyCollection') It seems to me that only the first namespace declaration is retrained. If I follow this insertion with the following query: declare namespace x ="xyz"; declare namespace y ="def"; collection('MyCollection')/x:test I get the following result: <t:test xmlns:t="xyz">good <s:test xmlns:s="">bye</s:test></t:test> Notice that the namespace for the prefix s is now empty. Further, if I reverse the order of the namespace declarations in the insert query: <t:test xmlns:s='def' xmlns:t='xyz'>good <s:test>bye</s:test></t:test> The query used above will not return a result (presumably because the xyz namespace has been dropped). Has anyone else encountered such issues? Currently we are working around this by saving the XML content to a file and using the Add process - which seems to work as expected. If possible, we would prefer to avoid this extra step of saving the XML to a temporary file before adding it to our BaseX database. Thanks, J Gager

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BaseX was successfully LISTED on FreeVistaFiles.com
by FreeVistaFiles.com 24 Jan '10

24 Jan '10

Hello DBIS Group, University of Konstanz, we just let you know that your software BaseX was successfully listed on FreeVistaFiles.com. Because we are listing quality software only, you may display our Listing image on any page. Here is the HTML code you could use to your Web page: <a href="http://www.freevistafiles.com/DBIS-Group-University-of-Konstanz+BaseX.html"><img src="http://www.freevistafiles.com/images/freevistafiles_listed_160x80.png" style="border:none;" width="160" height="80" alt="BaseX for Vista"></a> (you can download a copy of this image to keep it in your local web directory, and change the HTML fragment above to reference your local image rather than the one on our server) For current product BaseX update you should use this URL: http://www.freevistafiles.com/update-pad/DBIS-Group-University-of-Konstanz+… (we recommend you bookmark this URL for easiest future updates). And for others use this submission page: http://www.freevistafiles.com/submit/ Thank you, FreeVistaFiles.com Team. http://www.freevistafiles.com/

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how to change storage location of basex database
by Travis Webb 24 Jan '10

24 Jan '10

I've looked through the documentation but cannot find out how to do this. How do I change the path in which to store the basex files for a particular database? For example, if I create this database, create db test.xml test the basex files are, by default, stored in ~/BaseXData. How do I change this? -tjw

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XML database
by Steve Xu 22 Jan '10

22 Jan '10

Hello, I would like to know the usage of BaseX in industry and it's stability. It looks great! Regards, Steve Xu 647-747-6170(work) 416-564-7801(bb) 206AD74F(pin) steve.xu(a)rci.rogers.com steve.xu(a)rogers.blackberry.net This e-mail (and attachment(s)) is confidential, proprietary, may be subject to copyright and legal privilege and no related rights are waived. If you are not the intended recipient or its agent, any review, dissemination, distribution or copying of this e-mail or any of its content is strictly prohibited and may be unlawful. All messages may be monitored as permitted by applicable law and regulations and our policies to protect our business. E-mails are not secure and you are deemed to have accepted any risk if you communicate with us by e-mail. If received in error, please notify us immediately and delete the e-mail (and any attachments) from any computer or any storage medium without printing a copy. Ce courriel (ainsi que ses pièces jointes) est confidentiel, exclusif, et peut faire l’objet de droit d’auteur et de privilège juridique; aucun droit connexe n’est exclu. Si vous n’êtes pas le destinataire visé ou son représentant, toute étude, diffusion, transmission ou copie de ce courriel en tout ou en partie, est strictement interdite et peut être illégale. Tous les messages peuvent être surveillés, selon les lois et règlements applicables et les politiques de protection de notre entreprise. Les courriels ne sont pas sécurisés et vous êtes réputés avoir accepté tous les risques qui y sont liés si vous choisissez de communiquer avec nous par ce moyen. Si vous avez reçu ce message par erreur, veuillez nous en aviser immédiatement et supprimer ce courriel (ainsi que toutes ses pièces jointes) de tout ordinateur ou support de données sans en imprimer une copie.

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Re: [basex-talk] Questions about BaseX
by Miceli, Gino (FOMR) 22 Jan '10

22 Jan '10

Great! I'll look for that. Best wishes, Gino -----Original Message----- From: Christian Grün [mailto:christian.gruen@gmail.com] Sent: Friday, January 22, 2010 1:16 PM To: Miceli, Gino (FOMR) Cc: basex-talk(a)mailman.uni-konstanz.de Subject: Re: Questions about BaseX Hello Gino, by coincidence, we just decided to move BaseX to Maven! You can expect an update of our Subversion repository next week. Thanks for your feedback, Christian fyi: I've cc'd this mail to our basex-talk mailing list On Fri, Jan 22, 2010 at 1:11 PM, Miceli, Gino (FOMR) <Gino.Miceli(a)fao.org> wrote: > Dear Christian, > > Thanks for your response. It seems you are doing a great job on > BaseX. > > If I could make one suggestion, it would be nice if you could also > distribute your application with Maven. We use Maven for many of our > projects, and it would be great to pull the server part and require > dependencies automatically! > > I look forward to seeing more development on BaseX. I will check back > periodically to see how the project is progressing! > > Cheers, > Gino ___________________________ Christian Gruen Universitaet Konstanz Department of Computer & Information Science D-78457 Konstanz, Germany Tel: +49 (0)7531/88-4449, Fax: +49 (0)7531/88-3577 http://www.inf.uni-konstanz.de/~gruen

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Re: [basex-talk] Questions about BaseX
by Christian Grün 22 Jan '10

22 Jan '10

Hello Gino, by coincidence, we just decided to move BaseX to Maven! You can expect an update of our Subversion repository next week. Thanks for your feedback, Christian fyi: I've cc'd this mail to our basex-talk mailing list On Fri, Jan 22, 2010 at 1:11 PM, Miceli, Gino (FOMR) <Gino.Miceli(a)fao.org> wrote: > Dear Christian, > > Thanks for your response. It seems you are doing a great job on BaseX. > > If I could make one suggestion, it would be nice if you could also distribute > your application with Maven. We use Maven for many of our projects, and it > would be great to pull the server part and require dependencies > automatically! > > I look forward to seeing more development on BaseX. I will check back > periodically to see how the project is progressing! > > Cheers, > Gino ___________________________ Christian Gruen Universitaet Konstanz Department of Computer & Information Science D-78457 Konstanz, Germany Tel: +49 (0)7531/88-4449, Fax: +49 (0)7531/88-3577 http://www.inf.uni-konstanz.de/~gruen

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One Problem with XQJ API and one with XQuery Update
by Marcus Kessel 21 Jan '10

21 Jan '10

Hi, first of all: Great work! BaseX is the fastest/feature-rich XQuery Processor I have found so far. Currently, I'm working on a RESTful Service, where your processor is a great enhancement. So far, I've encountered a few problems. First: There is problem with XQuery Update, especially with "insert", which is not always reproducable. Example query: declare variable $newrec as node() external; insert node $newrec as first into basex:db('Recordings')/recordings The variable $newrec is bound to a "recording" Node with XQJ *.bindNode(new QName("newrec"), node, null); Sometimes, a ArrayIndexOutOfBoundsException is thrown in "org.basex.query.up.Primitives" at line 51. I did a quick hack, and replaced the null constraint with: } else if(l.length < pos) { l = new UpdatePrimitive[PrimitiveType.values().length]; l[pos] = p; But I think it's only a quick hack .. The second problem I've encountered is with "order by" clause and XQJ API. Order by has no effect, if I use the XQJ Api something like this: XQResultSequence result = null; XQExpression loadExp = null; try { loadExp = this.xqueryManager.createExpression(); result = loadExp.executeQuery(queryString); while(result.next()) { // do something } } But when I use the classes of BaseX directly, "order by" orders correctly. For example: QueryProcessor processor = new QueryProcessor(queryString, context); Result resultX = processor.query(); resultX.serialize(new XMLSerializer(out)); Sample query: element recordings { for $rec at $pos in basex:db('Recordings')/recordings/recording order by xs:dateTime($rec/startDate) descending return $rec } Any comments are appreciated ;) Thanks! Bye, Marcus

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Re: [basex-talk] BaseX Questions..
by Christian Grün 18 Jan '10

18 Jan '10

Dear Tyler, you might also be interested in looking into the following lecture/seminar slides: http://www.inf.uni-konstanz.de/dbis/teaching/ws0708/xml/24-Native.pdf http://www.inf.uni-konstanz.de/dbis/teaching/ws0708/dbissem/BaseXInside.pdf Apart from that and the listed publications.. http://www.inf.uni-konstanz.de/dbis/basex/publications.php we cannot provide you with more details on our implementation (yet). Basically, we are storing all data in a flat table representation. Table entries take 16 bytes each, and all entries are stored in blocks of 4kb, the order of which is referenced by a main memory directory. The nodes' pre values serve as node ids, which are unique during a single update transaction. If you need to know more, feel free to ask. Best, Christian FYI: I've forwarded this mail to the basex-talk mailing list. On Mon, Jan 18, 2010 at 4:21 PM, Tyler Corbin <094568c(a)acadiau.ca> wrote: > I don’t know if you can disclose this type of information – But I’m really > interested in the type of structures you’ve implemented for your BaseX and > how you achieved such quick updating and querying time. I’m doing some heavy > research into how different native XML Databases go about this, and it seems > BaseX is near the top (On performance). > > Do you have a more recent publication, which covers on how you go about > updating XML Structures? I’ve read one of your more recent publications on > your Database Architecture and some other things... but it doesn’t really > touch on your implementation of updates. > > > > - Since you don’t update the index structures for single updates, > do you have some type of “pending list” where all updates that are not > officially added to the index structures can still be accessed by the > processor? If not, can you briefly explain the data structure (if allowed)? > > - Also, how much compression do you get when your Database > Architecture is performed? > > > > > > I also have a few more questions, but I’m positive your recent publication > covers it. > > > > Thank you for your time! > > ~ Tyler > > > > > > > > > >

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Re: [basex-talk] Another index question
by Christian Grün 18 Jan '10

18 Jan '10

Hi Phil, in nearly all cases, the query optimizer will try to apply the existing index structures. As the XQuery syntax is much more versatile than SQL, this won't always succeed. - However, your query can be easily written. Three alternative writings, that all should access the index, look as follows: Query: //page[para[text() contains text "indiana"] and para[text() contains text "ninth"]] Alternative 1: //page[para/text() contains text "indiana"] [para/text() contains text "ninth"] Alternative 2: //page[para/text() contains text "indiana" and para/text() contains text "ninth"] Alternative 3: //page[para/text() contains text "indiana" ftand "ninth"] All three queries will yield different execution plans, and - to be strict - the third plan is not equivalent to the first two, as it expects the two query terms to occur in the very same text node. - Check out all of the alternatives to see which one works out best for you. Christian On Mon, Jan 18, 2010 at 7:25 PM, Phil Oliver <phil3(a)olivercomputing.com> wrote: > Another question regarding usage of full-text indices. My test database has > the full text indexing enabled with no options currently for simplicity > (e.g. wildcards, stemming, etc. disabled). > > A simple query such as: > > let $p:=//para[text() contains text "indiana"] > return $p > > executes rapidly using the FT index selection. However, if I try a more > complex query (designed to find two words on the same page): > > let $p:=//page[para[text() contains text "indiana"] and para[text() contains > text "ninth"]] > return $p > > the query plan does *not* use the FT index and takes a long time to execute. > > While this is a more complex query, it doesn't seem *really* complex, and > would be a common use case. Can you give me some idea as to why the FT > indices are not used in this instance, and if possible a suggestion on a > rewritten query that would use them? Is there a way to give hints to the > optimizer to always use them? > >

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Question on xQuery Updates.
by Tyler Corbin 12 Jan '10

12 Jan '10

If you could answer these questions or give a URL to my questions, It would be greatly appreciated... Can you explain how this program goes about dealing with xQuery Updates? Because Ive been getting some insanely quick inserting / deletion times and out of every open-source database system Ive tinkered with, Ive never seen anything as fast as this. I have ideas on how you go about this (havent had time to look at the source code) and I couldnt find anything in the documentation (other than the indexing processes.) (Sorry for such a short question, I was in a rush typing this.) Much appreciated and great release! Tyler.

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BaseX-Talk January 2010