November 2013 - BaseX-Talk - mailman.uni-konstanz.de

preprocessor instructions for BaseX XQUERY interpreters ?
by jean-marc Mercier 29 Nov '13

29 Nov '13

Hello, I have some questions about BaseX interpreter. 1) Is there a way to send preprocessor instructions to BaseX interpreter ? I am looking to a way to tell the interpreter to skip code based on external instructions, mainly to distinguish the behavior between debug / release modes. This is achieved in C++ with the macro set of instructions #define, #if, #endif etc... I was wondering whether there exists such a mechanism in XQUERY. Note : processor instructions might not be relevant for XQuery, since interpreters are heavily optimized. 2) Could you confirm that BaseX interpreter will not try to interpret "dead" code ? To emulate processor instructions with XQUERY, I am presently using dynamic local variable declarations as (declare function debug(){true()/false()}), and encapsulating my code with a lot of "if (debug()) then (.1.) else (.2.)". Can you confirm that BaseX interpreter skip looking at (.1.) or (.2.) accordingly to the debug function return value ? Cheers Jean-Marc

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New user requiring help in population of database
by Ando Roy 28 Nov '13

28 Nov '13

Hi all, I'm a new user of BaseX and would like to get myself up to speed with development as quickly as possible.Hope to get some pointers from the experts here, as I'm still picking up the concepts required in the use of XML Databases. I am experimenting with porting over some content from an existing RDBMS project to BaseX and would like to know how to go about doing it. I have already designed a XML schema based on my RDBMS model and would like to know how I can quickly go about populating the database in BaseX. Just a few quick questions here: 1. How should I go about creating the tree structure and its nodes (i.e. elements with attributes)? I'm a little confused (perhaps because I'm trying to approach it from a RDBMS perspective). 2. Is there a quick way to populate the database from some existing data sets (i.e. CSV or text files)? Thanks! Regards, Roy

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BaseX Interpreter / Eclipse integration issue ?
by jean-marc Mercier 28 Nov '13

28 Nov '13

Hi, Within my environment, I am experiencing some frustrating behavior of the Xquery Basex engine. I've done my best to single out the problem in the following XQUERY code : declare function local:wtf($x as item() ) {function() { $x}}; declare function local:dummy($f,$x) { if(fn:empty($f())) then local:wtf($x) else local:wtf(())}; declare variable $insert := local:dummy(function(){ () }, function() { (), ()} ); fn:count($insert()) The issues are : 1) executing this code yields an "Improper use? Potential bug?" exception (see details further on). 2) If I change the execution query to be fn:count(local:dummy(function(){ () }, function() { (), ()} )()) ( I just copy and pasted the value of $insert into the fn:count(..) ) then the query is executed normally, returning "1". 3) If I change the function declaration local:wtf as follow declare function local:wtf($x) {function() { $x}}; (I just removed "as item()"), then the query is executed normally, returning "1". Can you reproduce it with another environment ? Cheers, Jean-Marc Improper use? Potential bug? Your feedback is welcome: Contact: basex-talk(a)mailman.uni-konstanz.de Version: BaseX 7.8 beta 6aeaebf Java: Oracle Corporation, 1.7.0_05 OS: Windows 7, amd64 Stack Trace: java.lang.NullPointerException at org.basex.query.value.item.FuncItem.inlineExpr(FuncItem.java:308) at org.basex.query.func.DynFuncCall.optimize(DynFuncCall.java:58) at org.basex.query.func.DynFuncCall.compile(DynFuncCall.java:39) at org.basex.query.expr.Arr.compile(Arr.java:40) at org.basex.query.func.StandardFunc.compile(StandardFunc.java:60) at org.basex.query.MainModule.compile(MainModule.java:63) at org.basex.query.QueryCompiler.compile(QueryCompiler.java:70) at org.basex.query.QueryCompiler.compile(QueryCompiler.java:61) at org.basex.query.QueryContext.analyze(QueryContext.java:270) at org.basex.query.QueryContext.compile(QueryContext.java:253) at org.basex.query.QueryProcessor.compile(QueryProcessor.java:71) at org.basex.core.cmd.AQuery.query(AQuery.java:81) at org.basex.core.cmd.XQuery.run(XQuery.java:22) at org.basex.core.Command.run(Command.java:323) at org.basex.core.Command.execute(Command.java:92) at org.basex.server.LocalSession.execute(LocalSession.java:121) at org.basex.server.Session.execute(Session.java:37) at org.basex.core.Main.execute(Main.java:146) at org.basex.BaseX.<init>(BaseX.java:119) at org.basex.BaseX.main(BaseX.java:38)

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Reg : Group By Clause
by ChandraSekhar 28 Nov '13

28 Nov '13

Dear Team , I am following the below steps to execute my XQuery 1) I am Created collection with the MyFile.xml 2) I am running the query which is in attached file(query.txt) on the above collection 3) I am Grouping the C4 element for Grouping 4)I am running this query in java Java code : new XQuery(query).execute(context,fileoutstream); Query running properly when I am not using the group by clause Problem : If I use the group by ,exception is coming like out of main memory,can you please tell me Is their any alternate to reduce the memory when using group by Thanks & Regards Chandra Sekhar -- This message is for the intended recipient only. If you are not the intended recipient you are notified that disclosing, copying, distributing or taking any action in reliance on the contents of the information is strictly prohibited. __

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HTML serialization error
by Lars Johnsen 28 Nov '13

28 Nov '13

When converting files from xml to html, there appeared a serialization error saying something to the effect that x84 was an illegal html character. The files were written using file:write with parameter $params defined as: let $params := <output:serialization-parameters><output:method value="html"/></ output:serialization-parameters> When sending the html directly to the browser (not writing to file and using the above declaration), the browser (chrome) appeared to be ok, and displayed the full html. Processing the text through normalize-unicode() didn't help. The error persisted. Is there a way to fix the text before submitting it to file:write()? All the best Lars G Johnsen National Library of Norway

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how to develop our repository lib package?
by easy 28 Nov '13

28 Nov '13

hi,all, what's the extension package specifinition? can I install exist-db 's xar package into basex? -- 此致 easy 莫愁前路无知己，天下谁人不识君。

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Getting 404s through restxq
by Joe Templeman 26 Nov '13

26 Nov '13

Hi all, we are running basex through jetty and we're seeing basex get into a state where it returns nothing but 404, saying that no function for the request can be found even when they are completely valid paths and when we restart jetty, they work OK again. I can't seem to track down what state it ends up in to cause such a behavior, all of the files are there and nothing changes between restarts. Has anybody ever come across this before? Does anyone have any advice on how best to debug this issue? Thanks, Joe

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Line Number for Node
by Jeremy Moseley 26 Nov '13

26 Nov '13

Hi Guys, I am trying to find the line number of a node in the original XML source file. Is this information possibly stored in the database when the document is parsed? If that is not the case, is it possible to retrieve the original XML file after it has been inserted? Thanks, Jeremy

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Database-level locking
by Charles Duffy 24 Nov '13

24 Nov '13

Howdy -- Something I'd like to see would be the ability to make assertions about which databases a query will need a write lock on, such that the queries will fail at runtime if such an assertion was made but more locks are needed than were declared. This could allow more fine-grained locking to be used in places where global locks presently apply, without loss of safety. ...or is there an existing alternative that I've missed?

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document update timestamp?
by Pascal Heus 24 Nov '13

24 Nov '13

Is there any way to retrieve the date/time a document was pushed into a BaseX database? We have an external tool that needs to sync a folder holding XML files with a BaseX database (and we don't want to reload the entire content each time). Not an issue for new or deleted files but would like to be able to determine if a file/document in the DB is outdated. Note that a db/folder 'sync' feature could be nice to have as built-in feature. Thanks! *P

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