BaseX-Talk

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1 participants
5252 discussions

Basex with Multithreading
by Erol Akarsu 25 Oct '13

25 Oct '13

I am working on crawling data. I can see it is taking a lot of time because xquery is pulling web pages one by one. But popular crawlers like apache Nutch has multithreading support so it can open multiple socket connections to multiple sites so that it can crawl very fast. Can we make add multithreading support basex? So it can run multiple xquery functions in parallel and then merge results? Initially, merging results can be done manually. At least, if we can distribute loads to different xquery functions, that would be great. Erol Akarsu

2 4

do not interpret text nodes as embedded expressions (Expecting '}' but found...)
by Erdal Karaca 23 Oct '13

23 Oct '13

Hi all, How can I process this query in basex: let $x := doc(<a>main(){int i = 0;}</a>) return replace value of node $x with "" There are text contents that contain, for example, c code with curly braces which I do not want to be interpreted as embeded expressions. As a workaround I could escape the curly braces, But, is there a better way/option to suppress interpreting text contents that look like embedded expressions? Thanks!

3 4

Out Of Main Memory error while creating BaseX DB
by elangovan MuthuSwamy 23 Oct '13

23 Oct '13

Hi All, I am using BaseX to evaluate Xpaths (Xqueries) for larger size of XML files. I have created BaseX database initially using *CreateDB*.execute(ctx) API. And every time when I need to evaluate Xpath I open database using Open("database name") API and get a context. Using this context I evaluate the xpath. Once I complete my evaluation I close the context using Close.execute(ctx) API. My application is running without any issues. If the server runs for few weeks, I have observed "Out Of Main memory error" while updating the BaseX database. Could any one please help me in this issue. Is there any possibility of memory leak in BaseX in my work flow? Note: I am using same CreateDB(...) API to update / overwrite the existing Database. XML file Size may vary from 3Mb to 10 Mb. -- Regards, Elango.

2 1

Cache compiled expressions for use with QueryProcessor
by Erdal Karaca 22 Oct '13

22 Oct '13

Hi all, We have lots of non dynamic (i.e. do not change at run-time) queries/expressions that are always parsed/compiled using a new QueryProcessor instance. How to cache compiled expressions for use with QueryProcessor? Or can we just cache QueryProcessor instances? If yes, are QueryProcessor instances thread-safe? Thanks!

2 4

java.nio.channels.OverlappingFileLockException
by EV Narasimham 22 Oct '13

22 Oct '13

Hi, I have 3 application modules. One module, creates the xml database, the second/third module execute queries on the database (no updates are being performed on the database). When the second and the third module try accessing the database, once module is able to query the database while the other module ends up with the below exception. org.basex.core.BaseXException: Improper use? Potential bug? Your feedback is welcome: Contact: basex-talk(a)mailman.uni-konstanz.de Version: BaseX 7.8 beta Java: Oracle Corporation, 1.7.0_25 OS: Linux, amd64 Stack Trace: java.nio.channels.OverlappingFileLockException at sun.nio.ch.SharedFileLockTable.checkList(FileLockTable.java:255) at sun.nio.ch.SharedFileLockTable.add(FileLockTable.java:152) at sun.nio.ch.FileChannelImpl.tryLock(FileChannelImpl.java:1017) at org.basex.io.random.TableDiskAccess.lck(TableDiskAccess.java:183) at org.basex.io.random.TableDiskAccess.sharedLock(TableDiskAccess.java:170) at org.basex.io.random.TableDiskAccess.<init>(TableDiskAccess.java:83) at org.basex.data.DiskData.init(DiskData.java:122) at org.basex.data.DiskData.<init>(DiskData.java:92) at org.basex.core.cmd.Open.open(Open.java:68) at org.basex.core.cmd.Open.run(Open.java:35) at org.basex.core.Command.run(Command.java:344) at org.basex.core.Command.exec(Command.java:320) at org.basex.core.Command.execute(Command.java:77) at org.basex.core.Command.execute(Command.java:89) Below are the options being set: context.globalopts.set(GlobalOptions.GLOBALLOCK, false) ; context.globalopts.set(GlobalOptions.PARALLEL, 1) ; //After referring to https://github.com/BaseXdb/basex/issues/574<https://github.com/BaseXdb/basex/issues/574> When the same exercise is being undertaken on a windows machine, the above behavior does not occur. Regards Narasimham <https://github.com/BaseXdb/basex/issues/574>

2 2

Prefetch DOM root node (no lazy loading) using QueryProcessor command
by Erdal Karaca 19 Oct '13

19 Oct '13

Hi all, When querying a DOM Node (from DB on file system, i.e. no in memory DB) using QueryProcessor command: will the whole Node be fetched from the database or will parts of the Node's children still access the file system if not loaded yet? Thanks!

2 3

browser does not execute redirects
by Florian Eckey 19 Oct '13

19 Oct '13

Hi guys, i have a problem with redirects in basex. I have following function: declare %restxq:path("anyPath") function { "Some XQuery Code", <restxq:redirect xmlns:restxq="http://exquery.org/ns/restxq ">/restxq/anyOtherPath</restxq:redirect> }; This function I call with http://localhost/restxq/anyPath in my browser (Chrome). So I expect, that the browser gets the redirect an executes it. But it only returns: <restxq:redirect xmlns:restxq="http://exquery.org/ns/restxq ">/restxq/anyOtherPath</restxq:redirect> instead of the redirected page. In the attachment there is a screenshot. Is there anyone with the same problem or a solution? Regards, Florian PS: Are there any BaseX developer meetings in Germany?

2 1

Implementation of fn:collection
by Jeremy Moseley 17 Oct '13

17 Oct '13

Hi Guys, I was trying to use the fn:collectino function today, but I am having trouble understanding the implementation. From past experience, fn:collection($uri) (where $uri points to a document with a list of docs within it) has returned a sequence of all the documents. It appears that BaseX does not implement it this way. I have a database where I am storing a large number of documents, and I would like to have several collections inside which are subsets of these documents. I need to open these subsets quickly, and I thought fn:collection would allow me to do this. Is there any way to easily open these subsets using fn:collection (or a similar high performance function)? As of right now I am solving the problem by using a for loop to traverse the documents, but this is not fast enough for my needs. Thanks, Jeremy

2 6

OAI-PMH
by Lars Johnsen 17 Oct '13

17 Oct '13

Hello all I am looking into the possibility of using BaseX as an OAI-PMH metadata provider and harvester, and wondered if anyone has experience with it for this purpose. Specifically using BaseX as a repository with the http-service with xquery scripts for accessing and providing metadata records. Presumably, there aren't any limitations on the database side, and since the OAI-PMH protocol is all XML (http://www.openarchives.org/pmh/) it seems like a good idea to try and make it work. So if people on this list have any experience, I would like to hear from you. thanks, Lars G Johnsen National Library of Norway

1 0

problem with basexhttp
by Lars Johnsen 15 Oct '13

15 Oct '13

BaseX is installed by administrators on one of our server machines. When starting the http server, the followng message is displayed: $ ./basexhttp ..../basex/bin/src/main/webapp/WEB-INF/web.xml not found. which is a bit strange since the webapp folder is a sister folder to the bin folder. So why is it looking for webapp in ..../bin/src/main/ ? The webapp folder in itself do appear to contain all the relevant folders and documents. As it is similar to a working setup on another machine. All the best Lars G Johnsen National Library of Norway

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