Jeroen - no, purging a page updates the queries on that page, but not the semantic data itself. There are two cases I know of when you would want to update the data without resaving the page: setting data based on the results of a query, and setting data retrieved by the External Data extension. Thus, 'SemanticUpdateOnPurge' actually seems like quite a useful extension, and may even make sense as an (optional) feature within SMW itself. Apparently, it's tricky to get fully working, though...


On Wed, Jul 7, 2010 at 10:30 AM, Jeroen De Dauw <> wrote:

What functionality does this extension add exactly? When purging a page, SMW automatically updates all properties by itself right?


Jeroen De Dauw
Don't panic. Don't be evil. 50 72 6F 67 72 61 6D 6D 69 6E 67 20 34 20 6C 69 66 65!

On 7 July 2010 15:52, Daniel Werner <> wrote:
The people working in my wiki use the purge button very often to update
semantic data and query results so this certainly is the main cause for
the problem but perhaps not the only one.
I will deactivate this extension for a while. But it still could be
possible that the problem happens when saving a page or saving a page
and some additional circumstances.
I will report the result of the experiment soon.


On 07.07.2010 20:12, Yaron Koren wrote:
> I'd guess that this is indeed a result of your "SemanticUpdateOnPurge"
> extension, since I've never heard of it happening otherwise. I'd
> un-include that extension and see if the problem persists, to try to
> isolate the issue.
> -Yaron
> On Tue, Jul 6, 2010 at 10:50 PM, Daniel Werner <
> <>> wrote:
>     Hello,
>     I just discovered weird anomalies in the articles SMW properties in one
>     of my wikis. I can not say for sure since when this is happening since
>     the content of my wiki was growing over the last days and for some time
>     before there was nobody working on it.
>     Some weeks ago I updated to SMW 1.5, no 1.5.1 yet. So perhaps this is a
>     bug of 1.5 or it is something else but I am not sure if this ever
>     happened with SMW 1.4 or earlier. At least I never discovered something
>     like that in earlier versions.
>     So the problem is that article pages have properties of OTHER articles.
>     I discovered that this has something to do with the job queue. When a
>     article A updates its semantic data and then calls the job queue and
>     updates another page B, some (but not all) of the pages A properties get
>     passed over to page B!
>     This is really weird and makes a lot of trouble in my wiki. Also it
>     doesn’t happen every time the wiki processes a page from the job queue
>     but I can not say under which exact circumstances this happens.
>     One more thing is, I have the "SemanticUpdateOnPurge" extension
>     installed (I wrote this extension by my own) which updates a pages
>     attributes on a page purge. This bug happens a lot on page purge. I can
>     not even say for sure that it happens when saving the page, too.
>     So perhaps one of you more experienced developers could take a look into
>     the extensions code, perhaps there is something wrong with that but in
>     my opinion it should be save:
>     it is not much code, the most important part is:
>     $title = $parser->getTitle ();
>             $output = $parser->getOutput();
>             SMWParseData::storeData($output, $title, true);
>     Which is called onParserAfterTidy and only when action=purge && the
>     $title is the title of the page which got purged. So the job queue job
>     shouldn’t know any of this, right?
>     I have a bugtracker for my wiki, you can find some more information on
>     this in German language at
>     My wiki is
>     (I am Player140 there)
>     Would be very happy if we could solve this problem soon. I wonder if
>     it's a SMW bug or something else. Hope you can help me out with this.
>     Thanks a lot for any suggestions!
>     Daniel
>     ------------------------------------------------------------------------------
>     This email is sponsored by Sprint
>     What will you do first with EVO, the first 4G phone?
>     Visit <> --
>     _______________________________________________
>     Semediawiki-devel mailing list
>     <>
> --
> WikiWorks · MediaWiki Consulting ·

This email is sponsored by Sprint
What will you do first with EVO, the first 4G phone?
Visit --
Semediawiki-devel mailing list

WikiWorks · MediaWiki Consulting ·