February 2022 - BaseX-Talk - mailman.uni-konstanz.de

Database 'name' is being updated, or update was not completed.
by Jonathan Robie 20 Feb '22

20 Feb '22

I have some processes that update databases, taking a long time to do so. I would like other processes to be able to read the last complete snapshot while this happens. Is that possible? Jonathan

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Understanding Job Execution and Verification
by Eliot Kimber 18 Feb '22

18 Feb '22

I’m working out an “orchestration” module that manages running jobs that are functions from different modules, where the orchestrator dynamically constructs an XQuery that runs the specified function with the specified string parameters. I’m running jobs through a function that takes a sequence of jobs (XQuery strings) and calls jobs:eval() on each one in sequence: declare function orch:runJobs($jobs as xs:string*) as xs:string* { let $debug := util:logToLog('Have ' || count($jobs) || ' jobs:') let $debug := prof:dump($jobs) return for $job at $i in $jobs let $debug := (util:logToLog('Running job'), prof:dump($job)) return try { jobs:eval($job, (), map{'cache' : true(), 'log' : 'Running job: ' || $job}) } catch * { util:logToLog('orch:runJobs', ('Error running job ' || $err:code || ': ' || $err:description) ) } }; What I’m trying to achieve is a sequence of jobs run such that job 2 does not start until job 1 is finished and I don’t think that’s actually what I’m producing here. Most of these jobs are manipulating databases: dropping, creating, renaming, copying, etc., but a few will be longer-running—constructing indexes and whatnot. My question: What is the (best?) way to produce a sequence of jobs where each job waits for the preceding? Is it simply to do a jobs:wait(jobs:eval()) on each job or is there something better? Or am I missing a simpler way to perform this kind of job orchestration? Thanks, E. _____________________________________________ Eliot Kimber Sr Staff Content Engineer O: 512 554 9368 M: 512 554 9368 servicenow.com<https://www.servicenow.com> LinkedIn<https://www.linkedin.com/company/servicenow> | Twitter<https://twitter.com/servicenow> | YouTube<https://www.youtube.com/user/servicenowinc> | Facebook<https://www.facebook.com/servicenow>

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specifying explict path to database
by Eric Levy 17 Feb '22

17 Feb '22

I am targeting an application that would incorporate BaseX databases into larger projects, each following a standard file tree. As such, it is necessary for the application to interact with a database given by some path relative to the working directory. The application is structured as to provide query files through the command line in a standalone invocation. The documentation explains that the normal case is to resolve a directory in which all databases are stored, with each separate database in a sub-directory having the same name as the database. What support is available for the case in which the application must resolve the path to the database independent of the normal rules?

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Syntax-checker
by Ben Engbers 17 Feb '22

17 Feb '22

Hi, After I had formulated the query in Basex-GUI, I tried to execute the same multi-line query in R/RbaseX. Nada ;-( In R, one can use the paste function to concatenate strings. I use this function to build a string which is passed to the RbaseX-client. Example: Stmt_1 <- "for $i in 1 to 2 return $i" => OK Stmt_2 <- paste0("for $i in 1 to 2", => ERROR "return $i") It took 2 days of debugging before I found the error. Stmt_2 is concatenated to "for $i in 1 to 2return $i" and it is clear that this can't be executed. Instead of using the "paste0"-function I should have used "paste" which introdus a space between the strings to be concatenated. This works fine. My problem is that the server/my client does not give an error-message. And this leads me to following question: It would be helpfull if the syntax for the XQuery statement was checked before sending to the server. Where in the BaseX sources can I find the code for XQuery checking? Is it possible to translate tist code into R or is that way to difficult? Ben Engbers

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Namespaces, replace, and performance
by Jonathan Robie 17 Feb '22

17 Feb '22

I wrote a query that replaced roughly 470153 text nodes with an element that had two namespaces declared on it. It ran for several hours. I didn't need or want these namespaces, they were in the original source. I rewrote the query to remove the namespaces from these nodes before replacing the text node. I don't know how quickly it ran, but I think not more than 15 minutes, the first time I checked on it, it had already finished. I made no other changes to the query. Is this surprising? Or is this a general lesson about performance and updates that add namespaces low down in the hierarchy? Or ... Jonathan

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Long-running queries: command line or BaseX Gui?
by Jonathan Robie 17 Feb '22

17 Feb '22

Do long-running queries run faster from the command line, the GUI, or about the same from either? Jonathan

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COPY DB vs. CREATE DB
by Jonathan Robie 16 Feb '22

16 Feb '22

What's the easiest way to copy a database, whether or not there is an existing copy with a given name? If I load a database with CREATE DB, it replaces any existing database with the same name. I would like to do the same with COPY DB, but it raises an error if there is a database with the same name. And DELETE DB raises an error if there isn't a database with that name. So what's the right way to do this? Jonathan

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Accessing Java constant from XQuery
by Paul L. Merchant Jr. 16 Feb '22

16 Feb '22

Hi everyone, I'm using a Java library in XQuery in BaseX and I haven't been able to determine if there's a way to access a constant string (final static String... or even just final String...) in the Java class from XQuery. For example, if the Java class is declared as package my.module; public class MyModule { public static final String TITLE ="I'm a module!"; public String hello(final String world) { return "Hello " + world; } } The XQuery to call the "hello" method is import module namespace java = 'java:my.module.MyModule'; java:hello("World!") But is there any way to access "TITLE"? I'd like to share some constants between XQuery and Java, and I could write accessor functions for these constants, but it'd be cleaner if I didn't have to. Thanks!

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fn:format-date french translation
by Josselin Morvan 16 Feb '22

16 Feb '22

Hi everyone! It seems that there is no french translation for the fn:format-date() fonction with BaseX. Does anyone knows how and where I could add it to make it run with the format-date() function? Eventually, I could share the translation to make it accessible to all? Thanks a lot for your help, Best, Josselin

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Best Technique for Managing Sequences of Transactions Through Web/REST App
by Eliot Kimber 15 Feb '22

15 Feb '22

My validation dashboard is coming together and I’m now at the point of moving data update orchestration into the web app itself, rather than just in the shell scripts and single-transaction XQuery scripts I have now. My question is: What is the recommended technique, or what are the available options, for orchestrating a sequence of transactions in the context of a web application? For example, I have a button, not yet implemented, that needs to trigger update or creation of one of my indexes, which involves several transactions (drop temporary work database if it exists, create new work database, do work in that database, swap work result with current production database). I know I can use a sequence of redirects to get this and of course could also orchestrate it through JavaScript running in the browser. I’m trying to avoid JavaScript in this application simply to avoid complexity and keep as much of it as possible in XQuery. I’m also trying to work out the best way to present status and feedback for long-running actions—I know how to do the javaScript programming for this but again I’m hoping I don’t have to step up to that level of sophistication, at least not yet. So curious what techniques people use or recommend for transaction orchestration and monitoring. Thanks, Eliot _____________________________________________ Eliot Kimber Sr Staff Content Engineer O: 512 554 9368 M: 512 554 9368 servicenow.com<https://www.servicenow.com> LinkedIn<https://www.linkedin.com/company/servicenow> | Twitter<https://twitter.com/servicenow> | YouTube<https://www.youtube.com/user/servicenowinc> | Facebook<https://www.facebook.com/servicenow>

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