[Mondrian] sharing mondrian cache with biserver

Pedro Alves pmgalves at gmail.com
Wed Jun 6 19:18:48 EDT 2012

This is really a very important issue

I know for a fact that it was a nightmare to put all the pieces together
talking to the same cache.

The only missing piece seems to be olap4j.
Can we get it somehow to work the same as the others?

On Wednesday, June 6, 2012, Paul Stoellberger wrote:

> Yeah, downgrading makes sense. Ideally I'd prefer getting it directly /
> correctly from Pentaho as well.
> So, in the meantime do you have any idea if we can work around it?
> It seemed pretty important to Pedro, and knowing how fast such things move
> at Pentaho (they've been promising olap4j connections for a couple of years
> now) I don't think we can wait that long ;-)
> -Paul
> On Jun 6, 2012, at 11:50 PM, Julian Hyde wrote:
> As usual, I'll answer in the future tense... this may not help solve your
> problem, but this is how I'd like things to be.
> Pentaho should be getting its Mondrian connections from olap4j. (They're
> not, but they will be soon, they assure me.) If they (or anyone else) wants
> an old-style RolapConnection object, they can get it by calling
> connection.unwrap(RolapConnection.class). But it's perverse to start with a
> RolapConnection and try to wrap it as a MondrianOlap4jConnection.
> Julian
> On Jun 6, 2012, at 12:42 PM, Paul Stoellberger wrote:
> Hi,
> me and Pedro have done some more investigation and it appears like all of
> the pentaho code uses the mondrian.olap.DriverManager along with a already
> looked up datasource to create a Mondrian connection.
> Something along the following lines can be found in MDXConnection,
> PentahoXmlaServlet, or Reporting code:
>         DataSource dataSourceImpl =
> datasourceService.getDataSource(dataSourceName);
>         if (dataSourceImpl != null) {
>           properties.remove(RolapConnectionProperties.DataSource.name());
>           nativeConnection = DriverManager.getConnection(properties, null,
> dataSourceImpl);
> This code leads to a different connectionKey (cache key) that I can create
> with MondrianOlap4jConnection.
> We basically use the 100% same connection string (catalog url,
> everything), but still end up with a different key.
> Is there ANY way that we can turn a RolapConnection into an OlapConnection
> (MondrianOlap4jConnection if possible) ?
> I've looked at the MondrianServer code and thought maybe it was possible
> to create a RolapConnection just like all the pentaho code and then somehow
> use OlapConnection getConnection(), but I'm not sure whether this is even
> possible or not.
> Could someone shed some light on this and maybe help us come up with a way
> how we can achieve this shared cache?
> I don't quite get why the pentaho code does what it does, since we have
> the DatasourceService anyway..... if someone with some knowledge could
> clarify this that would be great as well.
> Thanks,
> Paul
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