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Re: [basex-talk] Strange path problem (revisited)
by James Ball 19 Jun '15

19 Jun '15

Kristian, It’s interesting your raise this - I was having trouble just yesterday working out why my colleague kept getting locked out of the server (I have fail2ban installed). Turns out he was going to http://ourdomain.com/dba/ (with a trailing slash) It all works if you go to http://ourdomain.com/dba (without a trailing slash) From my testing it looks like ‘dba’ and ‘dba/‘ both get caught by %rest:path(‘/dba’) which is redirected to ‘dba/databases’. However this means without the slash the browser interprets this as a redirect to http://ourdomain.com/dba/databases With the slash it is interpreted as a redirect to http://ourdomain.com/dba/dba/databases (which doesn’t exist and so after some attempts he was blocked). I only tested briefly yesterday but I couldn’t see immediately how to fix this (adding another %rest:path('/dba/') didn’t seem to work. But then I don’t know if the regex support affects that? Interested to hear others’ experience. Regards, James > > Message: 1 > Date: Mon, 01 Jun 2015 18:57:06 +0300 > From: Kristian Kankainen <kristian(a)keeleleek.ee> > To: BaseX <basex-talk(a)mailman.uni-konstanz.de> > Subject: [basex-talk] Strange path problem (revisited) > Message-ID: <556C80D2.1050101(a)keeleleek.ee> > Content-Type: text/plain; charset=utf-8; format=flowed > > Hello! > > I noticed that I get different results if I visit the following two urls: > http://myhost.domain/webappname/ > http://myhost.domain/webappname > > The only difference is the trailing slash. My RESTXQ has a path for '/' > but not for ''. My setup is with Tomcat. The difference seems to be the > basepath for the webapp. Static files etc are not found. This also > applies for the BaseX DBA: > > http://myhost.domain/webappname/dba/login resolves correctly > http://myhost.domain/webappname/dba/login/ doesn't find it's static > files etc. > > For my own webapp, it's the other way around --- with the trailing slash > everything works fine, without it the static files etc aren't found. > > Is it yet another Tomcat problem or can it be reproduced on your setups? > > Cheers! > Kristian

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performance of preceding/following axis
by Schopper, Daniel 18 Jun '15

18 Jun '15

Hi, I'm trying to use BaseX for linguistic queries on a TEI document containing annotated tokens (i.e. tei:w-elements with attributes). I'm specifically interested in distance queries that allow to search for combinations of token features within a given window (e.g. all nouns that have an adjective ending with 'lein' within a distance of 3.) Theoretically, this is rather easy to formulate with an XPath or XQuery expression, but performance is poor when the dataset gets a bit larger (in my case, I have a total of 190.000 tokens in my test document, attribute and text indexes created). This is what I essentially try to do as a simple XPath: declare default element namespace "http://www.tei-c.org/ns/1.0"; //w[@type = "NN"][(subsequence(preceding::w, 1, 3), subsequence(following::w, 1, 3))/@type = "ADJA"] Since tokens may be interwoven with markup, I have to use preceding::* or following::* A simple XQuery returning all matches including their context would look like this: declare default element namespace "http://www.tei-c.org/ns/1.0"; let $window := 3 let $matches := //w[@type = "NN"] return for $m in $matches let $pre := subsequence($m/preceding-sibling::w, 1, $window) let $next := subsequence($m/following-sibling::w, 1, $window) return if (($pre,$next)[@type = "ADJA"]) then <conc> <pre>{$pre}</pre> <match>{$m}</match> <next>{$next}</next> </conc> else () With $matches being a sequence of ca. 50.000 elements, a FLOWR is a bit too costly, I fear; limiting $matches to ~ 1.000 items performs within 5600ms (returning 154 items), but performance decreases rapidly after that (not to speak about setting a larger distance) . So, my question is: Is there a way to improve performance on operations like these (without resorting to changing the input document)? I'd be glad to provide my dataset off list, if this helps. Thanks, Daniel

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Gui
by meumapple 18 Jun '15

18 Jun '15

Hallo, I point out that In the last release, the number of repetions of a for clause is not displayed anymore on the top right corner of the GUI. This was very useful. Thanks, Joseph

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Low/high caps...
by France Baril 17 Jun '15

17 Jun '15

Hi, I moved a project from Windows to Mac (might be relevant or not) and after working with content for a while, I went to the GUI to create backups. Some of the DBs appears as duplicated and are listed with different caps. Ex. - D-archie - D-Archie The DBs listed in the GUI have the same size, they have the same content when opened in, even the same list of available backups, they look like they point to the same repository. In fact, the data repository only shows 1 folder and db:list() returns no duplicate, just the original names with the original caps. The WebDAV data source connection in Oxygen shows no duplicate either. I'm afraid of deleting the duplicate from GUI, as there is only one match in the data folder. I'll look in my code for a place where I might have typed the name with the wrong caps (I'm guessing a db:add or db:replace operation with the wrong caps would be the source of the problem). The request is for GUI and xquery to handle things in a similar fashion on a given platform. Either the caps make a difference, which means that trying to save content in a DB that doesn't exists (different caps = different names = different DBs) returns an error, or GUI handles caps as irrelevant and shows only 1 instance of the DB. Regards, France P.S. I'm on 8.2. -- France Baril Architecte documentaire / Documentation architect france.baril(a)architextus.com

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thinking outloud
by Rob Stapper 17 Jun '15

17 Jun '15

Hi Christian, Elaborating on the issue below and just thinking out loud. Would it make sense having to opportunity to evaluate a function body lazily? Consider the following function: declare function item:exists ( $item , $existProcessor , $emptyValue ) { if ( exists( $item)) then $existProcessor( $item) else $emptyValue } ; Even when called with an existing: $item, $emptyValue will be evaluated what could be an expensive evaluation. Having the possibility of lazy evaluation of the function body would prevent this. I’ve two questions: - does the above make sense? - does it make enough sense to be implemented in basex? If implemented: for keeping the code clean, specifying this laziness should be done within the function, not within the function call. I tumbled on the %basex:inline-annotation for global variables. This would do very nicely for specifying laziness for evaluating function bodies. declare %basex:inline function item:exists ( $item , $existProcessor , $emptyValue ) { if ( exists( $item)) then $existProcessor( $item) else $emptyValue } ; Best, Rob Van: Christian Grün [mailto:christian.gruen@gmail.com] Verzonden: woensdag 13 mei 2015 12:36 Aan: Rob Stapper; BaseX Onderwerp: Re: [basex-talk] unexpected behaviour If I get it right, you would also expect '!' not to be output in the following query, right? declare function local:f($a, $b) { if($a) then $b else () }; local:f((), trace('!')) In this case, you'll have to wrap your trace call in a function: declare function local:f($a, $b) { if($a) then $b() else () }; local:f((), function() { trace('!') }) Best, Christian On Wed, May 13, 2015 at 11:44 AM, Rob Stapper <r.stapper(a)lijbrandt.nl> wrote: Hi Christian, This is the best I can do without losing the essence of the issue. Sorry about the import, forgot to remove that one. The clue is in the “Query Info”-window. It shows: Evaluating: f1: 1 Compiling: ……. So function “local:f1#1” is unnecessarely evaluated with value 1. Success, Rob Van: Christian Grün [mailto:christian.gruen@gmail.com] Verzonden: woensdag 13 mei 2015 11:13 Aan: Rob Stapper CC: BaseX Onderwerp: Re: [basex-talk] unexpected behaviour Hi Rob, It usually takes me some time to understand new code, so could you possibly simplify the example as much as possible? For example, the import cannot be resolved, an empty squence is bound to $a, which means that one branch will never be called, and maybe you can simplify the partial function application as well.. Thanks in advance, Christian On Wed, May 13, 2015 at 9:55 AM, Rob Stapper <r.stapper(a)lijbrandt.nl> wrote: Hi Christian, Can you have a look at the attached program. Both items of the returned sequence of the program should do the same thing. Both do give the same, correct result: an empty sequence, but the first item unnecessarely triggers function: “local:f1#1” , while the second item doesn’t. This a pity since “local:f1#1” could be a time-consuming function. Cheers, Rob _____ <http://www.avast.com/> Afbeelding verwijderd door afzender. Avast logo Dit e-mailbericht is gecontroleerd op virussen met Avast antivirussoftware. www.avast.com <http://www.avast.com/> _____ <http://www.avast.com/> Afbeelding verwijderd door afzender. Avast logo Dit e-mailbericht is gecontroleerd op virussen met Avast antivirussoftware. www.avast.com <http://www.avast.com/> --- Dit e-mailbericht is gecontroleerd op virussen met Avast antivirussoftware. https://www.avast.com/antivirus

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Re: [basex-talk] Performing queries with a local function takes too much time
by Christian Grün 17 Jun '15

17 Jun '15

Hi Serdar (cc to the list), Your query amounts to more than thousands of index requests, and this eventually makes the query faster than when being executed sequentially. You can enforce sequential execution for the last for clause by using "eq" instead of "=". Next, you should factor out the content id path; otherwise, it will be evaluated thousands of times as well. The following query will be executed a bit faster: let $PlCts := //PlCt[environment = 'AIR']/@id for $PlGeTy in //PlGeTy[isOfPlCt/@href = $PlCts] for $PlSpTy in //PlSpTy[isOfPlGeTy/@href = $PlGeTy/@id] let $ContId := $PlSpTy/isOfCont/@href/string() for $Cont in //Cont[@id eq $ContId] return <done>{ $PlGeTy, $PlSpTy, $Cont }</done> Ideally, the query optimizer would detect that it's counterproductive to rewrite the last for clause to an index expression. However, decisions like this very much depend on the input data, and there are no simple heuristics for that. Hope this helps, Christian On Wed, Jun 17, 2015 at 1:39 PM, serdar ceran <bsceran(a)gmail.com> wrote: > Hi Christian, > > I have also another optimization issue on a query as I mentioned in Update > three section. > Could you help on this one? > > Thanks, > > Serdar > > > On Wed, Jun 17, 2015 at 12:57 PM, Christian Grün <christian.gruen(a)gmail.com> > wrote: >> >> Hi Serdar, >> >> Thanks for the hint. We have added a new GitHub issue to remember your >> request. >> >> Best, >> Christian >> >> [1] https://github.com/BaseXdb/basex/issues/1160 >> >> >> On Wed, Jun 17, 2015 at 11:18 AM, serdar ceran <bsceran(a)gmail.com> wrote: >> > Hi, BaseX team. I have a problem; Performing queries with a local >> > function >> > takes too much time to get the result. >> > >> > Please have a look at the Stackoverflow for more details. >> > >> > >> > Best regards; >> > >> > >> > Serdar CERAN >> > >> > > > > > > -- > Best regards; > > -- > B. Serdar CERAN > > Yaltes Company > Specialist Software Engineer > Tel: +905423993073 >

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Replication, partition and the CAP theorem
by ziiro_94＠freenet.de 15 Jun '15

15 Jun '15

Hello, I consider BaseX in the context of BigData and try to compare it with other noSQL databases. Yet, there is no replication or partition mechanism implemented and BaseX is a database with a single point of failure. Am I right? Thus, my question is, how can I classify the System BaseX regarding the CAP-Theorem? Yours sincerely --- Alle Postfächer an einem Ort. Jetzt wechseln und E-Mail-Adresse mitnehmen! Rundum glücklich mit freenetMail

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XQuery - math on elements within a sequence
by Luiz Matos 15 Jun '15

15 Jun '15

Hi everyone, I'm trying to execute a XQuery sum function in a multiplication of two XML elements, but it has been difficult to avoid the iteration in a sequence of elements. For example, considering this case: sample data: <Orders> <Order> <OrderKey>1</OrderKey> <LineItem> <LineNumber>1</LineNumber> <ExtendedPrice>70848.0000</ExtendedPrice> <Discount>0.0913</Discount> <ReturnFlag>A</ReturnFlag> <LineStatus>F</LineStatus> <ShipDate>1994-09-03</ShipDate> </LineItem> <LineItem> <LineNumber>2</LineNumber> <ExtendedPrice>64372.0000</ExtendedPrice> <Discount>0.0674</Discount> <ReturnFlag>A</ReturnFlag> <LineStatus>F</LineStatus> <ShipDate>1994-08-18</ShipDate> </LineItem> <LineItem> <LineNumber>3</LineNumber> <ExtendedPrice>64247.0000</ExtendedPrice> <Discount>0.0396</Discount> <ReturnFlag>R</ReturnFlag> <LineStatus>F</LineStatus> <ShipDate>1994-10-21</ShipDate> </LineItem> </Order> . . . </Orders> XQuery: <results> { for $lineitem in collection("tpch")/Orders/Order/LineItem let $returnflag := $lineitem/ReturnFlag let $linestatus := $lineitem/LineStatus where $lineitem/ShipDate <= "1998-08-31" group by $returnflag, $linestatus order by $returnflag, $linestatus return <record> <sum_disc_price>{sum($lineitem/ExtendedPrice*(1-$lineitem/Discount))}</sum_disc_price> </record> } </results> BaseX output: [XPTY0004] Item expected, sequence found: (element ExtendedPrice {...}, ...... My question: Considering this dataset model, how can I to write this query without change its semantics? I wouldn't want to use extra functions (e.g., fn:for-each), because I need to submit the same query in an limited xquery processor. Thanks in advance! -- Luiz Matos PhD student at Federal Fluminense University

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Internal cache for often accessed node sets?
by Gioele Barabucci 15 Jun '15

15 Jun '15

Hello, thanks to the all the answers I received in the thread "Optimization of a slow query with `//`" I can now make most of my queries much faster. However, while rewriting these queries I noticed that almost all the queries in my application could be rewritten in the form /tei:TEI/tei:text/tei:body//tei:ELEM[PREDICATE] and I wondered if it was possible to tell BaseX (or to have it understand by itself) that it can cache and reuse the results of /tei:TEI/tei:text/tei:body//tei:ELEM and only apply PREDICATE on the saved set of results. Is something like this available in BaseX? I suppose this could have a big impact on my queries, because the base query executes in about 250 ms and most of the other unoptimized queries in about 280 ms. This means that with the case in place they should complete in 30 ms (or 50 ms in more realistic terms). I tried sending via HTTP a dummy request for `/tei:TEI/tei:text/tei:body//tei:ELEM` together with a `<option name='cachequery' value='true'/>` to warm up the cache. Unfortunately all I got back was a "Unknown option 'CACHEQUERY'" error (with BaseX 8.2.1). Any idea why? Regards, -- Gioele Barabucci <gioele(a)svario.it>

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Re: [basex-talk] Optimization of a slow query with `//`
by Christian Grün 15 Jun '15

15 Jun '15

Hi Gioele, Queries with positional predicates such as the one that I posted in my last mail (in private, attached below) are now optimized as well. Best, Christian [1] http://files.basex.org/releases/latest/ On Mon, Jun 15, 2015 at 1:09 PM, Christian Grün <christian.gruen(a)gmail.com> wrote: > Hi Gioele, > >> I had a look at the info view but I fail to understand whether it is >> optimized or not. What should I look at? Sometimes I see a "Optimized Query" >> section, but it is not present for these two queries. > > I see. Yes, this means that the query is not rewritten. Instead, this > is one is optimized for index access, as the query info (and, > obviously, in this case the execution time) will show you: > > /descendant::tei:orth[text() = "arci"] > > I noticed that the query is not rewritten because of the positional > predicate (which are generally brain twisters in XQuery). Things look > better with the following query (but it may yield other results): > > /descendant::tei:orth > [text() = "arci"] > [ancestor-or-self::* > [@xml:lang][starts-with(@xml:lang, "san")] > ] > /parent::tei:form/parent::*[self::tei:entry or self::tei:re] > > The following query should take advantage of the index: > > for $n in /descendant::tei:orth[text() = "arci"] > where $n/ancestor-or-self::* > [@xml:lang][1][starts-with(@xml:lang, "san")] > return $n/parent::tei:form/parent::* > [self::tei:entry or self::tei:re] > > Best, > Christian

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