BaseX-Talk

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6 participants
5269 discussions

Atomic replacement of documents with a collection
by Andreas Jung 01 Aug '17

01 Aug '17

Hi there, I am finally heading for the first time to use BaseX in a customer project. We need to import XML based product catalogs in different languages. The catalog files should be updated each night without service interruption. What is the best strategy to update and replace an existing document without race condition? Should I uploaded the new version of a catalog under a different filename first and then use REPLACE? Is REPLACE atomic in the sense that an ongoing request will see the „old“ state of the document and new requests will see the new state of the document without any undefined state in between? Andreas

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Bug Report creating instance of BXDatabase
by Ignacio Hernandez-Ros 31 Jul '17

31 Jul '17

Hi, Bug Report! When running this code in a class on my own package I receive an IllegalAccessException Class<?> c = Class.forName("org.basex.api.xmldb.BXDatabase"); Database db = (Database) c.newInstance(); java.lang.IllegalAccessException: Class my.package can not access a member of class org.basex.api.xmldb.BXDatabase with modifiers “" I think the problem is that the class is not public. Best regards Ignacio

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Re: [basex-talk] Timezone and job start time
by Kendall Shaw 29 Jul '17

29 Jul '17

I think I can assume it is UTC. org/basex/util/DateTime.java contains: static { FULL.setTimeZone(TimeZone.getTimeZone("UTC")); } If there is a way to use the default timezone that would be better. Meanwhile, I made a module so that I can use source from JDK 1.8.x: package somewhere; import java.time.LocalDateTime; import java.time.ZonedDateTime; import java.time.ZoneId; import java.time.format.DateTimeFormatter; import org.basex.query.QueryException; import org.basex.query.QueryModule; public class Time extends QueryModule { public String zonedTime(String pattern) throws QueryException { return ZonedDateTime.from(LocalDateTime.now() .withHour(20) .withMinute(0) .withSecond(0) .atZone(ZoneId.systemDefault())) .withZoneSameInstant(ZoneId.of("UTC")) .format(DateTimeFormatter.ofPattern(pattern)); } } and, then in XQuery: jobs:eval(‘trace(“WENT”)’, map {}, map {‘id’: ‘somejob’, ‘start’: t:zoned-time(‘HH:mm:ss’)}) Kendall From: <basex-talk-bounces(a)mailman.uni-konstanz.de> on behalf of Kendall Shaw <kendall.shaw(a)workday.com> Date: Friday, July 28, 2017 at 2:37 PM To: BaseX <basex-talk(a)mailman.uni-konstanz.de> Subject: [basex-talk] Timezone and job start time declare namespace tz = "java:java.time.ZonedDateTime"; tz:now() returns 2017-07-28T14:23:08.334-07:00[America/Los_Angeles] Logs in dba seem to use the local time zone to display the date. The timestamp on resources is in UTC time, which is good. modified-date=”2017-07-28T21:17:53.347Z” But, do I have to use UTC time for scheduling jobs? For example: job:eval(‘…’, map {}, map {‘start’: ‘20:00:00’}) schedules the job for 5AM instead of 10PM, I think. If I can assume the time is UTC then I can figure out how to schedule the correct time. But, can I assume that it is UTC, or can I specify a Zoned time without a date? Kendall

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Timezone and job start time
by Kendall Shaw 28 Jul '17

28 Jul '17

declare namespace tz = "java:java.time.ZonedDateTime"; tz:now() returns 2017-07-28T14:23:08.334-07:00[America/Los_Angeles] Logs in dba seem to use the local time zone to display the date. The timestamp on resources is in UTC time, which is good. modified-date=”2017-07-28T21:17:53.347Z” But, do I have to use UTC time for scheduling jobs? For example: job:eval(‘…’, map {}, map {‘start’: ‘20:00:00’}) schedules the job for 5AM instead of 10PM, I think. If I can assume the time is UTC then I can figure out how to schedule the correct time. But, can I assume that it is UTC, or can I specify a Zoned time without a date? Kendall

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BaseX 8.6.5
by Christian Grün 28 Jul '17

28 Jul '17

Hi all, We have just released another version of our XML DBMS. The XQuery compiler of BaseX 8.6.5 provides some performance tweaks to improve typing of pre-evaluation expressions and, as usual, minor bug fixes. Visit basex.org to get the latest update. Your feedback is welcome. Have fun and a nice weekend, Christian

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org.basex.http source code and client-server mode
by Ignacio Hernandez-Ros 27 Jul '17

27 Jul '17

Hello, As this is my first post on the list I’ll introduce myself first. My name is Ignacio Hernandez-Ros (if you google my name there is only me and my son with that name…) and I’m from Madrid - Spain. About 15 years ago I learned about XQuery using “tamino” form Software-AG and now I’ve discovered baseX that looks amazing to me. I’ve been trying to configure the web administration portal to be used with a remote server with no success. It looks like it is not possible to take advantage of the client-server architecture from the Web Application http://docs.basex.org/wiki/Web_Application <http://docs.basex.org/wiki/Web_Application> I would like to know more about how the org.basex.http.restxq.RestXqServlet works and looking at the source code on GitHub I’m missing the org.basex.http package so I cannot see how can I improve it to allow it to connect to an existing server. I will appreciate any hint on how can I continue, either about where the source code is and how to contribute to it or how to set the WebApplication to run under client-server mode Best regards Ignacio

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Re: [basex-talk] Join operation and the database
by Christian Grün 27 Jul '17

27 Jul '17

Hi Giuseppe, > If I compare values just using one indexed string (the one in @v), this is the fastest way (about one second on my machine). It depends on the value you are looking for. If it only occurs once in your database, the lookup will be very fast (in database terms, this is called a “high selectivity”). > If I compare against two distinct indexed values, their order matters, in that -if I understand correctly- the database uses the index only(?) for the first values. Exactly. You can enforce index access by directly using db:text(). > I see that [p = $t/@o and f = $t] is much slower than [f = $t and p = $t/@o]. I calculated that on average f contains about 8 characters while p always contains 9. However, (Ancient Greek) characters in f are heavier ( 2 or 3 bytes each) than the (Latin) ones in p (1 byte each). Can this be the reason why [f = $t and p = $t/@o] is evaluated faster? This doesn’t matter (as long as the string length does not exceed MAXLEN [1]). The critical question is how many index results you will get for a single lookup. See the following example: declare variable $txts := doc("tlg0001.tlg001.perseus-grc2.xml"); for $t in ($txts//t)[position() = 1 to 10] return ( "* " || $t/@o || ": " || count(db:text("splitted-db", $t/@o)), "* " || $t || ": " || count(db:text("splitted-db", $t)) ) The first lookup will return much more hits than the second one. You can call the following function to get a complete list of all index entries: index:texts('splitted-db') Cheers, Christian [1] http://docs.basex.org/wiki/Options#MAXLEN

1 0

Join operation and the database
by Giuseppe Celano 27 Jul '17

27 Jul '17

Hi, I performed join operations between many files and a dictionary. The files contain tokenized texts, where one finds word forms + fine-grained POS tags. Look at the following file: https://raw.githubusercontent.com/gcelano/POStaggedAncientGreekXML/master/t… <https://raw.githubusercontent.com/gcelano/POStaggedAncientGreekXML/master/t…> The dictionary, which contains word forms + fine-grained POS tags + lemmas, can be found here: https://github.com/gcelano/LemmatizedAncientGreekXML/tree/master/uniqueToke… <https://github.com/gcelano/LemmatizedAncientGreekXML/tree/master/uniqueToke…> I created a database for the dictionary and wrote a query (here simplified) like the following: for $t in $s/t (: t are the tokens in the file containing the tokens :) let $match := $lemm//d[./p = $t/@o and ./f = $t/text()] (: $lemm//d are the single entries in the dictionary :) return $match I see that if I use this query, it is slow, as if the processor cannot use the database indexes (./p and ./f). The situation does not seem to improve with ./p/text() and ./f/text(), which I would assume to be equivalent to the former because of atomization. On the contrary, if the same information contained in ./p and ./f are merged together and put in an attribute (see @v in the dictionary files) and this is compared against the values in the text (after concatenating them properly), the join operation is super fast (i.e., the index for the values in the attributes are used by BaseX). Does anyone know why? I have been able to get my results via the above (slow) comparison, but I would like to know what the cause of the problem was, if possible. Thanks. Best, Giuseppe Universität Leipzig Institute of Computer Science, Digital Humanities Augustusplatz 10 04109 Leipzig Deutschland E-mail: celano(a)informatik.uni-leipzig.de E-mail: giuseppegacelano(a)gmail.com Web site 1: http://www.dh.uni-leipzig.de/wo/team/ Web site 2: https://sites.google.com/site/giuseppegacelano/

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Access output:media-type value from QueryProcessor
by Andrew Tsui 26 Jul '17

26 Jul '17

Hi, Is it possible to get the value of "output:media-type" through QueryProcessor? I am currently trying to use BaseX as a view renderer for a Spring MVC application. The view is rendering fine using embedded BaseX. However, I can't figure out how to get the "output:media-type" value from the XQuery so that I can set the response header during runtime. I can set the content-type through the controller in Spring. But I would rather not have to do it in two separate places. Below is the relevant code snippet from the view renderer. try(QueryProcessor proc = new QueryProcessor(query, context)) { Iter iter = proc.iter(); //response is HTTPServletResponse response.setContentType(????); try(Serializer ser = proc.getSerializer(response.getOutputStream())) { for(Item item; (item = iter.next()) != null;) { ser.serialize(item); } } } Any suggestion? Thanks Andrew

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JSON to map
by Florian Wagner 19 Jul '17

19 Jul '17

Hey there, I'm probably missing something but please bear with my as I'm new to XML databases and XQuery. So what I've done is put JSON documents into BaseX using the REST interface and PUT requests. Now I want to use them in a RESTXQ handler. Loading the document using "db:open" will return me a document-node() but I'd like a map instead for simpler use and automatic types (I'll be outputing JSON again). The only thing I could come up with and that works is using "Content-Type: application/json;format=basic" when uploading and then: parse-json(xml-to-json(db:open(...))) But that seems very complicated and wasteful. Is there no other way? Regards Florian Wagner --- Universitaetsbibliothek Tuebingen Wilhelmstr. 32, 72074 Tuebingen IT-Abteilung, Raum B109 +49(0)7071/29-77860 http://www.ub.uni-tuebingen.de

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