BaseX-Talk

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1 participants
5252 discussions

BaseX XQuery vs. python / lxml performance
by Ronny Möbius 30 Mar '12

30 Mar '12

Hi, we use now for a couple of years XML files for organizing the schedule of lectures in our institute. The amount data for one semester is about one megabyte. For presenting the schedule on the web we use currently python in combination with the C-based lxml XPath implementation. Only basic selecting nodes happens on the layer of lxml, but the most of intelligence is implemented in filtering python lists and lists of dictionaries. We read the xml data from hard disk and parse them into lxml objects. >From time to time we thought about storing the data in a XML database as this seems intuitive. One main point is, that we need some sort of transaction management, because different applications may manipulate the files simultaneously. Now I gave BaseX a try and implemented one basic output of our online schedule in XQuery. Soon I noticed, that all of the intelligence should be managed inside XQuery as it should return the full-prepared html for presenting online. Unfortunately we now have the impression, that we did not gain speed - to the contrary the query itself needs more execution time than the whole corresponding ready interface (including the user interface etc.) I'm now interested in your general opinion about this: Is it surprising, that the XQuery implementation than the lxml/python one (For me it is, as I thought the indices etc. created when importing the data should decrease computational affords in searching the tree)? Is there some catch in my approach? May the reason be bad designing the query? I would appreciate to hear from you, Ronny

5 7

Updates failing due to "opened by another client" on a system running only basexhttp
by Charles Duffy 30 Mar '12

30 Mar '12

Howdy -- I recently had an update run via the REST interface fail due to the database being "opened by another client". This would be unsurprising were it taking place on a workstation where a concurrent process such as basexgui might have been running, but the host in question was a server, with its basexhttp instance controlled by system init scripts, running as a dedicated user, and otherwise unlikely to be interfered with by a separate process. There are, however, multiple concurrent REST clients using that same HTTP server. As basexhttp should be the only service directly accessing the underlying database on this host, this surprises me -- my expectation is that the transaction monitor would defer any execution of an update until a full lock could be grabbed, preventing it from interfering with other read or update actions happening within the same process. Is this expectation valid? If not, what do I need to do to be able to apply updates to a database with minimal disruption to readers?

4 5

Declarations for external variables not enforced
by Charles Duffy 30 Mar '12

30 Mar '12

Howdy -- Using the REST interface, I'm currently able to do the following: <rest:query xmlns:rest="http://basex.org/rest"> <rest:text>$foo</rest:text> <rest:variable name="foo" value="bar"/> </rest:query> ...and get back "bar" as a result. Note the lack of a "declare variable $foo external" line. I haven't read the spec to determine permissibility of this behavior, but it does come in handy at times (particularly, for permitting maximally terse one-liners). Is this something likely to go away in the future? Thanks!

4 3

Out-of-band logging from XQuery functions
by Charles Duffy 29 Mar '12

29 Mar '12

Howdy -- Is any mechanism available for queries to log errors out-of-band without modifying their return values? Something like a wrapper around log4j would be perfect; right now I'm using file:append(), but as this requires my queries to know where the system administrator wants things to be logged to (which should be an entirely separate concern), it's very far from ideal.

2 2

wie geht es dir$
by areaurbana 29 Mar '12

29 Mar '12

1 0

Using stemming via the BaseX API
by Michael Wilson 27 Mar '12

27 Mar '12

I’m working on a hobbyist project of mine, and am having trouble with stemming when running queries from a java app (I’m using the BaseX API to search XML japanese dictionary files via a custom swing/GUI application). Specifically, I receive the error message: “[FTST0009] No tokenizer available for language 'Japanese'.” I do have the etc/ja folder present. This problem does not occur when I run the same query from the BaseX GUI. I replicated the same class path I observed in the basexgui.bat file: I added basex.jar, igo-0.4.3.jar, lucene-stemmers.3.4.0.jar, xml-resolvers-1.2.jar, tagsoup-1.2.jar to the Path environment variable, but it didn’t help. Does anyone have any ideas on how I can make stemming work from my application? I appreciate any insights or solutions.

3 2

CSV, text equivalents to json:parse() and parse-xml()?
by Charles Duffy 27 Mar '12

27 Mar '12

Howdy -- For JSON and XML, mechanisms to generate an in-memory document from an xs:string() exist. For CSV or text inputs, however, I'm unclear on how to do this without declaring options and invoking db:add() -- not ideal when the content being handled is intended only for transient, one-time-only processing. Pointers? (If there exists a mechanism to invoke any available parser without necessarily creating a new database, this would be ideal). Thanks!

2 1

Mechanism to serialize maps in output?
by Charles Duffy 27 Mar '12

27 Mar '12

Howdy -- Right now, trying to inspect a map (ie. returning one from a query) results in FOTY0012. This is unfortunate from the perspective of allowing users to examine the objects their logic creates. Has thought been given to defining a serialization-friendly way of representing maps, perhaps as XML entities under their own namespace?

4 3

Usin Basex for Desktop Application
by Sandeep Yohans 27 Mar '12

27 Mar '12

Hello Sir/Madam, I am interested in using BaseX for my Desktop Application which I am developing using Java SE. Is it possible to use BaseX in a Desktop Application (Standalone Application) which will be installed on a computer with no internet connection or intranet? Looking forward to hear from you. -- Sandeep Yohans Developer AIR Infotech Nagpur - India www.airinfotech.in

2 1

How I can use Basex as embedded python datastorage?
by Andrey Ganyushkin 26 Mar '12

26 Mar '12

Hi All How I can use Basex as embedded python datastorage? It's possible? I can't find the answer to this question. -- BEST REGARDS, Andrey Ganyushkin

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