Re: [Semediawiki-user] Release preview and SVN warning

[Markus K. <ma...@se...>]

On Donnerstag, 5. Juni 2008, Samuel Richardson wrote:
> This sounds great Markus, I had noticed some performance slowdown on
> very large queries which I alleviated by installing eAccelerator
> however this sounds like it's going to help as well :)

The bottlenecks addressed by the store should be quite different from the ones 
that eAccelerator addresses. eAccelerator improves PHP performance, e.g. when 
formatting large query results for output. This should be noticeable in most 
page loading times. The new store, in contrast, significantly reduces the  
memory and CPU needs even of larger queries (in extreme cases, a hard query 
can occupy a DB for minutes, even after PHP timed out, which effectively 
freezes the server during that time; SMW has its query complexity parameters 
to disallow such queries). 

Using both in combination might be even better (though I did not try out how 
well eAccelerator works with SMW).

Cheers,

Markus

>
> Thanks,
>
> Samuel Richardson
>
> T: (0405) 472 748
>
> richardson.co.nz
>
> On 05/06/2008, at 6:30 AM, Markus Krötzsch wrote:
> > As we plan to release SMW 1.2 in the next weeks, it is time for me
> > to provide
> > a preview of intended new features.
> >
> > == New Store ==
> >
> > As a major change, there will be a new storage backend
> > implementation with
> > completely new internals. From a user viewpoint this means:
> >
> > * most operations, especially queries, are faster,
> > * full top-level disjunctions in queries will work using the keyword
> > "OR"
> > (this can be disabled if desired),
> > * full equality support (based on redirects) will be the default,
> > and it will
> > not have major performance impacts,
> > * caching and optimisation strategies for Very Large Wikis to increase
> > performance for applications with large categories,
> > * some specific performance issues are alleviated (Special pages),
> > * annotated interwiki links are likely to be supported.
> >
> > The general performance gain will hopefully let you use larger and
> > more
> > powerful queries, which you did not dare to use now, or that really
> > ran too
> > slow on your site. I know that many people care little about actual
> > *speed*
> > but rather about query power, but this is really the same in many
> > cases.
> >
> > The downside of this is that you will have to run the update script to
> > initialise the new store after upgrade. Alternatively, the old store
> > will
> > still be available as an option, but without the new features.
> >
> > From a developer's viewpoint, not much should change. Most of the
> > API is
> > completely untouched. A separate email on the devel list will sum up
> > the
> > changes later on. If you still use code with explicit SQL queries to
> > smw-tables, reconsider. We expect most SMW extensions to be able to
> > adopt to
> > the new version quickly or to just work right away.
> >
> > PostgreSQL compatibility is still not checked (the old store should
> > work
> > there, though). I will inform the developers once the new DB layout is
> > somewhat more stable to ask for support on that issue.
> >
> > == Other features ==
> >
> > Another important new feature are automatic updates. Currently, if
> > you create
> > an annotation, and then edit the property (e.g. change its
> > datatype), then
> > the old annotation is not updated. The new version will take care of
> > this. A
> > similar feature is in place for semantic templates: if a template is
> > changed,
> > affected pages will automatically update as well.
> >
> > Various minor extensions in query expressivity are also on our list,
> > and there
> > are some patches to include as well. Better query printout control
> > is one
> > thing, another are inverse properties and (closed world) negation in
> > queries,
> > but it is not clear yet whether this will be quite ready for this
> > release.
> >
> > Of course there will also be much new/extended translations,
> > adjustments to
> > fully support the upcoming MediaWiki 1.13, and various bugfixes.
> >
> > == SVN Warning ==
> >
> > The development version of SMW will soon be updated to use the new
> > store by
> > default. This may be slightly experimental at first, and in any case
> > you must
> > run the usual refresh script to make it work initially (see INSTALL
> > for
> > details). It is also possible to drop the old storage DB tables to
> > free up
> > memory, but there is no simple script/admin function for that yet.
> >
> > == Outlook ==
> >
> > We intend to go for further expressive features in upcoming
> > releases. Examples
> > are transitive properties and other "rules", in combination with a
> > caching
> > architecture that allows these more challenging features to work in
> > practice.
> > We also still plan to provide a better implementation of Type:Date
> > (the
> > cleaner DB implementation will help there too), some new query
> > printers, and
> > support for MediaWiki specific attributes such as page modification
> > time in
> > queries.
> >
> >
> > Cheers,
> >
> > Markus
> >
> > --
> > Markus Krötzsch
> > Semantic MediaWiki    http://semantic-mediawiki.org
> > http://korrekt.org    ma...@se...
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-- 
Markus Krötzsch
Semantic MediaWiki    http://semantic-mediawiki.org
http://korrekt.org    ma...@se...