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

BaseXException
by Mark Boon 09 Dec '10

09 Dec '10

This is a bit an off-the-wall request but I figured it doesn't hurt to throw out here as an idea. When I have an error in my query I typically get a BaseXException saying something like: org.basex.core.BaseXException: Stopped at line 42, column 55: [XPST0003] Expecting ")", found """. However, it doesn't show me the query. Since I generate (sometimes large) queries automatically, this message by itself is not always very helpful (to put it very mildly). Either I print all my queries in their entirety, something that results in a dazzling amount of output. Or I jump through some hoops and try to keep my last query so it can be printed alongside the exception. Both are not very satisfactory solutions. I was thinking though how nice it would be if the exception could print the query for me. And the icing on the cake would be if (in the above example) it would print an extra line just after line 42 with 54 spaces and ^ at column 55, so I get an arrow pointing out where the error is without me having to count to 42 first and then to 55. Whatcha all think? Personally, I think it's such a good idea I was thinking of doing it myself. If the BaseX6.3 source were available, that is. Mark Boon

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BaseX 6.3.3 - problems to list some docs if path specified (in some cases)
by Jan Vlčinský 09 Dec '10

09 Dec '10

Hi I get problems listing some documents Attached is compressed database. Test scenario - listing all docs - OK for $doc in collection() return base-uri($doc) returns file:/D:/opt/BaseX/snapshot file:/D:/opt/BaseX/mydata.xml file:/D:/opt/BaseX/path/to/data/mydata.xml file:/D:/opt/BaseX/mydata2.xml file:/D:/opt/BaseX/path/to/data/mydata2.xml file:/D:/opt/BaseX/DDRTest/ddr/live/JSDI_NDIC_20100111_00000751.xml file:/D:/opt/BaseX/DDRTest/ddr/live/JSDI_NDIC_20100111_00000752.xml This is OK Test scenario - listing path/to/data documents - OK for $doc in collection("DDRTest/path") return base-uri($doc) for $doc in collection("DDRTest/path/to") return base-uri($doc) for $doc in collection("DDRTest/path/to/data") return base-uri($doc) in all cases returns file:/D:/opt/BaseX/path/to/data/mydata.xml file:/D:/opt/BaseX/path/to/data/mydata2.xml This is also OK Test scenario - listing ddr/live docs - ERROR for $doc in collection("DDRTest/ddr") return base-uri($doc) for $doc in collection("DDRTest/ddr/live") return base-uri($doc) does not return anything. This is bad. How was the database created All DDRTest/path/to/data documents were added via command line client. Note, that those documents are very simple like <root/> All DDRTest/ddr/live documents were added using Python API Note, that when adding those documents, XML declaration was present as seen from my log record add as JSDI_NDIC_20100111_00000752.xml to DDRTest/ddr/live *<?xml version="1.0" encoding="utf-8"?>*<DOC version="3.0" id="14662257-ca70-48a1-b2b8-0c34d6f4cef4" country="CZ" DataSet="extended"><INF sender="JSDI_NDIC" receiver="TRAFFICINTELLIGENCE" transmission="HTTP"><DAT><EVTT version="2.01" language="CZ" /><SNET type="GN" version="8.12" country="CZ" /><UIRADR structure="4.2" version="593" /></DAT></INF><MJD count="1"><MSG id="{8ad5a3b7-261d-b1f0-0126-1dd076cd0045}" version="1" type="TI" planned="false"><MTIME format="YYYY-MM-DDThh:mm:ssTZD"><TGEN>2010-01-11T15:39:38+01:00</TGEN><TSTA>2010-01-11T15:33:17+01:00</TSTA><TSTO>2010-01-11T16:33:17+01:00</TSTO></MTIME><MTXT language="CZ">Od 11.1.2010 15:33 do 16:33 v ulici Okružní v obci Klášterec nad Ohří okres Chomutov , délka 176m; Klášterec nad Ohří, ul. Okružní u č.p. 557, okr. Chomutov nehoda; OA srazilo chodce, bez zranění</MTXT><MEVT><TMCE urgencyvalue="N" directionalityvalue="1" timescalevalue="(D)" diversion="false"><EVI eventcode="201" updateclass="3" quantifier="1" eventorder="1"><TXUCL language="CZ">Nehody</TXUCL><TXEVC language="CZ">nehoda</TXEVC></EVI><TXTMCE language="CZ">nehoda </TXTMCE></TMCE></MEVT><MLOC><TXPL>v ulici Okružní v obci Klášterec nad Ohří okres Chomutov , délka 176m</TXPL><SNTL coordsystem="S-JTSK" count="4"><COORD x="-825701" y="-996639" /><STEL el_code="160642" /><STEL el_code="160642" /><STEL el_code="160771" /><STEL el_code="160951" /></SNTL></MLOC><MDST><DEST CountryName="Česká republika" RegionCode="60" RegionName="Ústecký" TownShipCode="3503" TownShip="Chomutov" TownCode="563129" TownName="Klášterec nad Ohří"><STRE StreetCode="147290" StreetName="Okružní" /></DEST></MDST></MSG></MJD></DOC> Attached is also log file from BaseX. Jan On Tue, Oct 26, 2010 at 1:16 PM, Jan Vlčinský <jan.vlcinsky(a)gmail.com>wrote: > Thanks Michael > The option to specify path in collection is good one. > Just for others to see how it behaves: > > I have collection name "Pokus" > add as item01.xml to "dir/subdir" <root1/> > add as item02.xml to "/dir/subdir" <root2/> > creates two documents there (both path versions works the same, with or > without slash) > base-uri reports names starting "file:/D:/opt/BaseX/dir/subdir" > (what might confuse a bit, but not much) > > xquery for $doc in collection("Pokus/dir/subdir") return base-uri($doc) > selects both items properly (of course showing the 'D:/opt/BaseX/' inside > of the base-uri result string). > > xquery for $doc in collection("Pokus/") return base-uri($doc) > selects all items in the collection, not only from the root > > xquery for $doc in collection("") return base-uri($doc) > selects all items in the currently open collection, if one used open > <collection>, otherwise it complains about no default collection. > > I did not find any way how to query relative path in current collection > without naming it. No real need for this now. > > With best regards > > Jan > > On Tue, Oct 26, 2010 at 11:37 AM, Michael Seiferle < > michael.seiferle(a)uni-konstanz.de> wrote: > >> Hi Jan, >> >> I am sorry but at the moment there is - to my knowledge - way of >> specifying a custom prefix to the base-uri(). >> You can as well, starting from 6.3, provide a path to documents inside a >> collection via: >> >> for $doc in collection('test/dir') >> return base-uri($doc) >> >> Anyway, regarding your issue: >> >> for $doc in collection('test/dir') >> return replace(base-uri($doc),'file:/path/foo/bar/','') >> >> might do the trick. >> >> Kind regards >> Michael >> Am 26.10.2010 um 11:16 schrieb Jan Vlčinský: >> >> I tried many ways how to specify target - without and with slash and >> backslash - no change. >> Is there any way to manage that? >> >> Jan Vlčinský >> >> PS: Be sure this is not a problem if it is not possible. it would be only >> a bit nicer. >> >> >> > > > -- > *Jan Vlčinský* > Slunečnicová 338/3, 734 01 Karviná Ráj, Czech Republic > tel: +420-597 602 024; mob: +420-608 979 040 > skype: janvlcinsky; GoogleTalk: jan.vlcinsky(a)gmail.com > > -- *Jan Vlčinský* Slunečnicová 338/3, 734 01 Karviná Ráj, Czech Republic tel: +420-597 602 024; mob: +420-608 979 040 skype: janvlcinsky; GoogleTalk: jan.vlcinsky(a)gmail.com

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Dynamische Elementnamen ?
by Burkert, Michael 08 Dec '10

08 Dec '10

Hallo ! Frage: Ist es möglich Knotennamen dynamisch zu vergeben ? Konkret: <mod:Elementname1> soll dynamisch erzeugt werden. Abstrakt: <{$nodename}> Statische Vergabe von Knotenamen: declare function Model:Fkt ( $classes as xs:string) as node()* { for $class in $classes return <mod:Elementname1 rdf:about="{$class}"> </mod:Elementname1> }; Mit freundlichen Grüßen Michael B

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How to delete selected documents from database
by Jan Vlčinský (CAD) 07 Dec '10

07 Dec '10

Hi So far I was adding documents and querying using Python API (generally sending commands to BaseX). Now I need to delete some documents. What is the most effective method? 1. drop db I would have to recreate it very soon. I am a bit concerned by other clients being connected to the same database 2. loop in Python performing delete command one document by one 3. do some sort of xquery in style "for $doc in collection() return (delete base-uri($doc))" Note, that this does not work, but there might be some way like this similar to insert or update mechanism Any ideas or hints? Thanks for advice Jan -- *Ing. Jan Vlčinský* CAD programy Slunečnicová 338/3, 734 01 Karviná Ráj, Czech Republic tel: +420-597 602 024; mob: +420-608 979 040 skype: janvlcinsky; GoogleTalk: jan.vlcinsky(a)gmail.com http://cz.linkedin.com/in/vlcinsky

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BaseX 6.3.3
by Christian Grün 06 Dec '10

06 Dec '10

Dear all, we've just released another minor version of BaseX, which is also linked now from the download page (http://basex.org/download) Finally, BaseX 6.5 will be published in January '11. Along with the official release, we'll relaunch our homepage, containing some commercial offerings.. stay tuned! Here's the changelog of Version 6.3.3: [ADD] XQuery: "ft" module added to extended XQuery Full Text with useful features; see http://basex.org/xq-ft [ADD] Command: DROP BACKUP added to drop database backups [ADD] GUI: new menu items "Add documents" and "Delete documents" [ADD] GUI: new menu item "Manage" to backup/restore/rename/drop databases [MOD] XQuery: "db" and "file" modules updated: http://basex.org/xquery [MOD] System.getProperty("user.dir") added as optional home directory [MOD] GUI: menu structure updated [FIX] Command: ADD modified to support the addition of larger documents [FIX] GUI: highlighting of search terms in text editors [FIX] GUI: file chooser supports new extensions: *.xql, *.xquery, ... [FIX] Server: StressTest All the best, Christian

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A couple of technical issues
by Mark Boon 04 Dec '10

04 Dec '10

I ran into a few separate issues. Since they concentrate on the same piece of code, I address them simultaneously. In my program I have the following method: private void processEventTriggers() { try { ByteArrayOutputStream stream = new ByteArrayOutputStream(); String inQuery = "collection()/event/@in/string()"; XQuery inputQuery = new XQuery(inQuery); inputQuery.execute(_context,stream); String input = stream.toString(); String processQuery = "collection()/trigger_set/trigger[@name='"+_currentTrigger+"']/matches"; System.out.println("Process Event: "+processQuery); QueryProcessor processor = new QueryProcessor(processQuery, _context); Iter iterator = processor.iter(); Item item; while ((item=iterator.next())!=null) { BXNode node = (BXNode)item.toJava(); String pattern = node.getAttributes().getNamedItem("pattern").getNodeValue(); // Pattern regexp = Pattern.compile(pattern, Pattern.CASE_INSENSITIVE); // Matcher regexpMatcher = regexp.matcher(input); // System.out.print("'"+input+"' matches '"+pattern+"'"); // if (regexpMatcher.matches()) // System.out.println(" = true"); // else // System.out.println(" = false"); String matchQueryString = "matches('"+input+"','"+pattern+"','i')"; System.out.print("Match Query: "+matchQueryString); XQuery matchQuery = new XQuery(matchQueryString); stream.reset(); matchQuery.execute(_context,stream); if (stream.toString().equals("true")) { System.out.println(" = true"); if (executeCommands(node)) break; } else System.out.println(" = false"); } } catch (BaseXException exception) { exception.printStackTrace(); } catch (QueryException exception) { exception.printStackTrace(); } } What this does is it queries the database for an input item and then matches this input to a set of 'matches' nodes. When a node matches it starts executing a series of commands, which are mostly XQuery commands themselves. The first issue I have is that it seemed a bit inefficient to use an XQuery to match a regular expression. The section commented out matches the same regular expression. Unfortunately, I bumped into a few cases where the Java implementation mistakenly returns 'false' whereas the BaseX implementation returns 'true'. I can't complain really about BaseX here. Actually, kudos for providing a proper implementation, because I had assumed it would simply delegate this functionality to the Java regexp API. But I was a bit surprised to find that the Java regular expressions implementation seems to be broken. My question now is, can I call the BaseX 'matches()' function directly? Because I think that would be much more efficient. A more serious issue I have is that the XQueries that are executed in the 'executeCommand()' call occasionally insert and delete nodes into collection()/memory sub-elements. And it also can recursively call processEventTriggers() again. Most of the time this works fine, but occasionally I get the following error: Exception in thread "main" java.lang.RuntimeException: Possible bug? Feedback is welcome: basex-talk(a)mailman.uni-konstanz.de BaseX 6.3.2: Data Access out of bounds [pre:403, indexSize:4, access:4 > 3] at org.basex.util.Util.notexpected(Util.java:46) at org.basex.io.TableDiskAccess.cursor(TableDiskAccess.java:323) at org.basex.io.TableDiskAccess.read1(TableDiskAccess.java:92) at org.basex.data.Data.kind(Data.java:324) at org.basex.query.item.DBNode$4.next(DBNode.java:272) at org.basex.query.path.IterStep$1.next(IterStep.java:45) at org.basex.query.iter.NodeIter.next(NodeIter.java:1) at org.basex.query.path.IterPath$1.next(IterPath.java:66) at org.basex.query.path.IterPath$1.next(IterPath.java:1) at BotCommandProcessor.processEventTriggers(BotCommandProcessor.java:285) at BotCommandProcessor.processEvent(BotCommandProcessor.java:262) at BotCommandProcessor.executeCommands(BotCommandProcessor.java:364) at BotCommandProcessor.processEventTriggers(BotCommandProcessor.java:305) at BotCommandProcessor.processEvent(BotCommandProcessor.java:262) at BotCommandProcessor.main(BotCommandProcessor.java:442) Now I'm not entirely sure, but I suspect that the iterator is affected either by the insert/delete operations or by the nesting of the iterator process. Or a combination of the two. I could somehow understand this if the queries that are being executed would affect the set of triggers it's looping over, but that is not the case. I did find an ugly way around this problem but I'm afraid it could get me into trouble later. So any feed-back about what might be the best way to fix this would be appreciated. Mark Boon

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Introducing PAD Submit Worker
by ShareSoftware24 01 Dec '10

01 Dec '10

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Inserting nodes into xquery result sets
by Charles F. Munat 01 Dec '10

01 Dec '10

I have a database like this: <data> <templates> <template> <id>123</id> <content> <html> <head><title>My Template</title></head> <body><text/></body> </html> </content> </template> </templates> <pages> <page> <id>456</id> <content> <p>This is some text.</p> </content> </page> </pages> </data> I want to write an XQuery that results in this: <html> <head><title>My Template</title></head> <body><p>This is some text.</p></body> </html> So <text/> is replaced by <p>This is some text.</p> Here is the start of an XQuery select: for $x in /data/templates/template[id='123']/content/* for $y in /data/pages/page[id='456']/content/* return $x That gets me the template. How do I insert $y in place of $x/body/text ? I've searched all over with no luck. I can do this in the business logic, but so much better to do it in the query. Also, I'd like to be able to do this recursively. Is that possible? Do I have to write my own function for this? Thanks much for any help! Chas.

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Surprising function behavior
by Mark Boon 30 Nov '10

30 Nov '10

I bumped into some surprising function behavior. I have the following query: declare namespace math = "java:java.lang.Math"; declare function local:choose-phrase ( $phrase as xs:string ) as xs:string { let $prefix := local:choose( ("Absolutely, ", "It's likely that ", "The odds are good that ", "There's a fairly good chance that ", "There's a light chance that ", "It's uncertain that ", "Chances are not good that ", "It's doubtful that ", "It's unlikely that ", "There's no way that ") ) return fn:concat($prefix,$phrase) }; declare function local:choose ( $arg as xs:string* ) as xs:string { let $count := fn:count($arg) let $random := math:floor(math:random() * $count) + 1 return $arg[xs:integer($random)] }; local:choose( ( "Phrase 1", "Phrase 2" ) ) When I execute this (say in the GUI tool) it's supposed print either "Phrase 1" or "Phrase 2". Instead it prints a random choice from the function 'choose-phrase' as if it was called with an empty string as argument, which is very strange. When I remove the 'choose-phrase' function altogether, the query behaves correctly. If I then paste the 'choose-phrase' after the 'choose' function, it also behaves correctly. But declaring 'choose-phrase' before 'choose' gives me an unexpected result. The only thing I can think of is that 'choose-phrase' calls 'choose' which is declared later. I don't know if that's actually allowed. But even so, it should give an error instead of seemingly doing something random.

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Re: [basex-talk] User-defined functions
by Christian Grün 23 Nov '10

23 Nov '10

Hi Mark, (I'm passing this on to the mailing list..) > At the moment my function block is not very long. But I expect this is > likely to change, as I'm using XQuery as a sort of programming > language where 'users' can add functions. Moreover, there will be > cases where they'll be executing thousands of queries and the total > execution time should ideally take no more than a second or two in the > most extreme circumstance. > > At this time I don't experience any performance problems, BaseX is > very snappy. But I'm still in the experimentation phase and I'd like > to avoid spending a lot of time building a framework that later may > turn out to be unworkably slow. Regarding the complexity and size of function blocks, our users haven't reported any bottlenecks yet. Instead, bad performance is mainly due to XQuery expressions that are difficult, or impossible, to optimize. But, no doubt, it might make sense to precompile complex XQuery code that takes hundreds of KB, or even MB. Right now, precompilation of XQuery code isn't supported in BaseX > Another thing I ran into is that updating doesn't seem to be allowed > within functions. So I'm now looking into using XSLT to solve these > issues for me. On the one hand by prefixing the query with the > function declarations that are actually used in the query, and through > templates that would substitute updating function-calls by the > function-body. I'm also new to XSLT so I'm not sure if that will work, > but it seems worth giving it a try. Updating is no problem in XQuery functions: you'll have to add the "updating" specified to a function declaration: declare updating function ... { ... }; A general restriction of XQuery is that an expression cannot both update and output items. As an example, the following query is invalid: delete //node, 1 to 10 Instead, you can perform local updates by applying the transform expression: copy $a := ...nodes to be modified... modify ...update on $a... return ...e.g., $a... > P.S. extracting the xsl-stylesheet from the file-header from an XML > file and then applying it to itself is a bit ugly, does anyone know if > there is a (JAXP) way to get an XML file with its stylesheet already > applied automagically? Maybe this won't be necessary anymore.. Hope this helps, Christian

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