BaseX-Talk August 2019

basex-talk@mailman.uni-konstanz.de

28 participants
28 discussions

ePub zips via REST and functional XQuery
by Majewski, Steven Dennis (sdm7g) 22 Aug '19

22 Aug '19

BTW: I was pleasantly surprised to discover that when I made a BaseX database with an ePub zip file, and selected the appropriate options ( Parse files in archives, add other files as raw files ) I was able to serve and view the ePub files thru the rest interface, and links from the TOC to other document parts, as well as images in the ePUB all worked. I’m also enjoying learning to use some of the higher order function capabilities of XQuery 3.1 . The arrow syntax and the partial function application seem to be a great way to build a pipelines of transforms that can mix xslt:transform with XQuery functions . The results here aren’t very useful — I was just learning and testing the syntax, but this uses the partial application ‘?’ Syntax to convert functions of N-args to functions of 1 arg, and build a list of 1-arg functions to feed to fold-left. The use case would be to create a map of lists of pipeline functions to be applied for different targets. Not sure if maintaining pipeline lists is a better way to manage this than just building pipelines using arrow => operator, but I was just trying to explore some of the possible methods. let $docid := 'SIB/sibv060.xml' let $t1 := xslt:transform( ?, "/projects/SIB/add_id_bov.xsl" ) let $t2 := xslt:transform( ?, "/projects/XTF/xtf.lib/style/dynaXML/docFormatter/tei/teiDocFormatter.xsl", map{ 'docId' : $docid }) let $t3 := function($in) { $in//* } let $pipe := ( $t1, $t2, $t3, function($x) { $x ! name(.) }, distinct-values#1 ) let $chain := function( $a, $b ) { $b($a) } return fold-left( $pipe, doc($docid) , $chain )

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Db:list-details()/@modified-date
by Majewski, Steven Dennis (sdm7g) 21 Aug '19

21 Aug '19

I thought I could use db:list-details($db)/@modified-date to select the resources that have most recently been updated ( to generate an OAI or RSS feed ) however, on doing a db:replace of one of the resources, I’m either not seeing the date change at all, or I’m seeing the modified-date of all of the resources update together. I find an explanation in the archives: https://www.mail-archive.com/basex-talk@mailman.uni-konstanz.de/msg09668.ht… > Exactly: Nothing will be replaced in BaseX if your source and target > XML node is identical (this holds true for both documents as well as > any other node in a document). > > Please note that XML documents have no individual timestamps in BaseX. > Instead the timestamp of the database will be changed if nodes are > changed. > Do I parse that correctly in saying that when I try to replace a document with an identical document, it doesn’t register as an update, but when I do change and update the document, it changes the timestamp for the whole database, and there is no timestamp for individual resources ? So I assume that if I want to track updated resources, I would have to either add timestamps to the documents themselves, or else track this info somewhere else, maybe in SQL and use sql: functions from within BaseX. Maybe best method is to add timestamp as a processing instruction or comment to avoid any changes to the body of the document: insert node processing-instruction modifiedDateTime { current-dateTime()} as first into $D That would work if doing the updates from an XQuery script and calling db:replace and then adding the timestamp, However, not very reliable if the resource can be updated by another method ( WEBDAV for example ) unless there is a way to trigger xquery function on update. I find from searching the mailing list archives a link to an issue discussing adding database triggers, but it appears to be on hold: https://github.com/BaseXdb/basex/issues/1082 Any news on this or suggestions of alternatives ? — Steve Majewski

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read file permissions
by Ветошкин Владимир 21 Aug '19

21 Aug '19

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BaseX GUI just spins?
by Buddy Kresge 21 Aug '19

21 Aug '19

I have a situation that I don't know if others are experiencing - but it has happened quite a bit over the last week with 9.2.4 I have the below function. declare function base:employeeIdMostRecentInstancesBetweenMap ($rangeBeginDate as xs:date, $rangeEndDate as xs:date, $employee as element()?, $query as function(xs:date, xs:date, item()*) as item()*) as map(xs:string, item()*) { let $allInstances := $query($rangeBeginDate, $rangeEndDate, $employee ) let $resultsMap := base:instancesBetweenMap($allInstances, $rangeBeginDate, $rangeEndDate) return $resultsMap }; I then wanted to put in a statement that would throw an error and return some information so that I could debug a situation. Basically I just added one statement to throw the error. Now when I run, BaseX Gui just spins and spins and spins. No value is returned. Never gets to this statement. I take out the let statement and it all works again. declare function base:employeeIdMostRecentInstancesBetweenMap ($rangeBeginDate as xs:date, $rangeEndDate as xs:date, $employee as element()?, $query as function(xs:date, xs:date, item()*) as item()*) as map(xs:string, item()*) { let $foo := error(xs:QName("err"), concat("val: ", "here - this is where I would put the info I wanted to display." )) let $allInstances := $query($rangeBeginDate, $rangeEndDate, $employee ) let $resultsMap := base:instancesBetweenMap($allInstances, $rangeBeginDate, $rangeEndDate) return $resultsMap }; Any insights you can provide would be greatly appreciated. Buddy

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Best methods for improving query speed with large joins
by Marko Niinimaki 21 Aug '19

21 Aug '19

Dear all, I have a database with suppliers/parts/orders/customers/listitems and I'm trying to gain performance for queries like "sum up all orders where customers are in Japan". This results to many joins of documents representing each type of entity. With a relational database I'd use foreign keys. It looks like BaseX supports DTD's. Would creating DTD's improve the query speed? In the mailing list I saw only one reference to this https://www.mail-archive.com/basex-talk@mailman.uni-konstanz.de/msg02586.ht…. In the response "a DTD-aware XQuery processor can supply the id() and idref() XPath functions. However, these do not work across documents, and the values must be legal XML identifiers. Having said that, most XML databases make indexes, so joins using FLWOR and values will work based on values." Based on that, I'd need to create a DTD for a structure that has id's and idref's and the corresponding document would be 1 GB large (to contain all the suppliers/parts/orders/customers/listitems). Would this make sense? Mark

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Built-in collations
by Zimmel, Daniel 21 Aug '19

21 Aug '19

Hi, I found out that after adding the third-party jar to the classpath as described here (http://docs.basex.org/wiki/XQuery_3.1#Collations), I can finally alphanumeric-sort my map:keys: map:keys($map_ev) => sort('http://www.w3.org/2013/collation/UCA?lang=de;numeric=yes') Which I like a lot. Are there any plans on having this already shipped with BaseX in future releases? Thanks, Daniel

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Map serialization
by Giuseppe G. A. Celano 19 Aug '19

19 Aug '19

Hi When maps are serialized, the text nodes of an element (e.g., <g>r</g>/text()) are serialized without quotes and tests with "instance-of" show that they actually are text nodes: Couldn't they be serialized with quotes? I see that with data(), the text is serialized with quotes although it is xs:untypedAtomic. Is there a reason why the text node is kept as such and, for example, no casting/atomization happens when it becomes a value in a map? Thanks. Best, Giuseppe

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Binary module
by Giuseppe G. A. Celano 14 Aug '19

14 Aug '19

Hi I am playing around with the binary module. I have two simple questions: 1) convert:string-to-base64("sàà") returns sàà : what does it mean? I see in the documentation that I need to use string() to see the value of xs:base64Binary (c8Ogw6A=), but shouldn't xs:base64Binary already be outputted as c8Ogw6A= ? (This is actually displayed in the Info Panel). 2) bin:length(convert:integers-to-base64(x)) always returns one number, no matter how big the number is. In the documentation I read that the output of bin:length should be the size of binary data in octects: how is that possible? Thanks, Giuseppe

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Declaring namespaces in xquery:eval call
by Buddy Kresge 13 Aug '19

13 Aug '19

I am trying to do something like xquery:eval("some:function()"), and when I go to execute I get "[XPST0081] No namespace declared for 'some:function' I did read the reference that was sited in your documentation for how to declare a namespace binding (http://www.jclark.com/xml/xmlns.htm), but am still having no luck Can you help me with what the map should look like given the following attempt: like xquery:eval("some:function()", map { ????? } ) Thanks in advance. Buddy Kresge

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console.log ?
by Majewski, Steven Dennis (sdm7g) 10 Aug '19

10 Aug '19

Is there an equivalent to console.log or xsl:message in XQuery or BaseX ? I know I could use the basex file: module to write to a file, but is there anything that works with the logging system to direct output according to the context ? — Steve Majewski

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BaseX-Talk August 2019