[Mondrian] multiple schemas? cache management?

Ati Rosselet ati.rosselet at gmail.com
Wed Dec 5 04:32:31 EST 2007

Yup.. pretty much what we were/are doing.. only we used the clearCache()
whenever an import occurred (user performs import).  Unfortuately we need to
upgrade mondrian since the version we were/are using is REALLY old.. and
doesn't seem to have aggregate table support, or at least not as it should..
and the new version doesn't support clearCache.   What I'm looking for with
mondrian 2.4 is a way to specify the whole cube in a "region" for
invalidation (similar to clearCache()).  I'll take a look at the
DataSourceChangeListener in any case...  thanks...

On the multiple schema XML side... anyone have any experiences/ideas/hints?
I mean.. is there some mondrian function that I need to call via the API or
something before I switch schemas?  Or do I need to approach this
differently ???


On Dec 5, 2007 10:21 AM, Pappyn Bart <Bart.Pappyn at vandewiele.com> wrote:

>  Hi Ati,
> I have a real world application that is running good at more than 15 sites
> for now.  My database has two fact tables, both identical in layout.  One
> contains the hot data (today), the other one the archived data.  My system
> is a sort of real-time olap (data is updated all the time, but only
> reflected every 5 minutes in the hot fact table).  My database is updated
> using transactions.
> The first is implemented in a cube with all cache turned off and does not
> have aggregate tables.  The second one has cache turned on and has aggregate
> tables.  Both are combined in a virtual cube, both share the same
> dimensions.
> The aggregate tables are calculated at night.  I use the
> DataSourceChangeListener to check whether an aggregation table is
> changed.   I use RolapSchema.clearCache(); to flush the cache after all
> aggregation tables are done.  I flush dimension cache using the
> DataSourceChangeListener, in that case, there is no need to clear the full
> cache.  I have a special table in my database containing the name of the
> table and the time the aggregation is done.  This way I can communicate
> using the DataSourceChangeListener and the database without having to know
> about the ETL process that is running in C++.
> I use the previous version of mondrian (2.3.2), I know the function
> RolapSchema.clearCache() was deprecated and I assume it no longer exists
> in the latest version.  I don't see the benefit of only flushing certain
> parts of the cube, since a) I don't know what to flush b) Almost everything
> is changed.  Also I assume that dimension cache is still not flushable (I
> might be wrong about that), besides using DataSourceChangeListener.
> There is a period at night where results might be wrong using this
> approach, but since at that time, my users only check data from today
> (monitoring purpose), there are no huge problems.
> The performance is ok (2-10 sec for a report), the database is 5 - 10 GB
> for 1 year data.
> I am using this approach for over a year now, and is actively running on
> multiple sites, without any problems.
> While I developed DataSourceChangeListener for the 2.3.2 release, I do not
> have the time for the moment to check if it is still working in the latest
> release.  I had to stop taking the latest version of mondrian, because my
> application is using almost all features that mondrian contains.  And every
> build of mondrian broke something in my application.  So maintaining
> DataSourceChangeListener was a never ending story and I had no time left for
> developing my own application.
> There are multiple users that are using the system at the same time, I
> also had to develop special features for mondrian for this (for cache
> flushing and real time results). Not sure if they are still in place in the
> latest release.
> Kind regards,
> Bart
>  ------------------------------
> *From:* mondrian-bounces at pentaho.org [mailto:mondrian-bounces at pentaho.org]
> *On Behalf Of *Ati Rosselet
> *Sent:* dinsdag 4 december 2007 18:44
> *To:* Mondrian developer mailing list
> *Subject:* [Mondrian] multiple schemas? cache management?
> In previous versions of mondrian, I could just provide a different schema
> with a query (notably through jpivot) and the data for that schema would be
> loaded and cached... seperately.  This was important because we had multiple
> schemas in different files, each with their own set of roles etc .. and it
> worked fine keeping them seperate.  To my suprise, when we ported to the new
> mondrain, it seems to just cache the FIRST schema file we provide, and
> ignore any others... thus of course leading to the
> hierarchy/dimension/member not found errors.  My question is simply... what
> changed.. and is it still possible to use multiple schemas via jpivot
> especially....
> a seperate question - we're having a tough time getting our brains around
> the new cache invalidation - is there any way to just say.. ok... reload
> everything (or pertaining to a certain cube??)?   We have to reload all the
> aggregate tables using a procedure anyways, so pretty much everything is
> affected.. or can be... is there no way to just say cache.clear().. or
> something?  Does anyone have any real life examples of cache management they
> could share?
> Cheers
> Ati
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