[Mondrian] Integrating data from non-JDBC data sources
jhyde at pentaho.com
Mon Aug 17 19:16:09 EDT 2009
I'm not going to suggest a place to look in the code. What you want to do is
I have put 'in-memory dimensions' on the roadmap. These dimensions would be
sourced from a regular JDBC table, in the same database, but would just be
cached so that most of the time Mondrian would read from memory. To
guarantee that Mondrian NEVER needs to join is much harder; and to add a
plugin architecture for dimensions, harder still.
You could experiment with an EII tool such as http://www.jboss.org/teiid.
But by far the easiest option is to just do the ETL using Kettle.
> -----Original Message-----
> From: Torsten Schlabach [mailto:tschlabach at gmx.net]
> Sent: Monday, August 17, 2009 8:37 AM
> To: jhyde at pentaho.com; Mondrian developer mailing list
> Subject: Re: [Mondrian] Integrating data from non-JDBC data sources
> Hi Julian!
> > You don't want to access every row in your fact table,
> > then join to the time dimension, filter out those in year 2008 and
> > aggregate at the quarter level. You want the database to
> join, filter
> > and aggregate simultaneously.
> Of course this is the ideal case, but the world isn't always
> ideal. And
> your data source isn't always where you wish it was.
> Simply put, for my problem, I have two alternatives:
> 1) Do the classic ETL thing, i.e. use Kettle (pardon: PDI) to get
> everything into one nice database
> + I will be faster.
> - I don't have live data.
> 2) Access data directly from different sources
> + I will have live data.
> + I don't need to create a separate database which holds the
> analytic data
> + I can live with one less tool (Kettle / PDI)
> - It will be slower.
> But practially speaking, I expect some 10.000 records in my non-JDBC
> datasource and the datasource would even allow filtering, for example,
> for the year. I don't think that processing the couple of
> 1.000 records
> for one year in memory should cost too much performance, but it would
> just be convenient.
> If I were to make some experiments, could you give me some hints at
> which classes to look in the Mondrian source code?
> Julian Hyde schrieb:
> > In the early days we discussed custom member readers, that
> would allow you
> > to programmatically create a dimension that is not backed
> by a JDBC table.
> > In principle you could also create a custom cell reader, to
> replace a JDBC
> > fact table.
> > The problem is, a lot of the power comes from joining fact tables to
> > dimension tables. You don't want to access every row in
> your fact table,
> > then join to the time dimension, filter out those in year
> 2008 and aggregate
> > at the quarter level. You want the database to join, filter
> and aggregate
> > simultaneously.
> > I guess if you could present a fact table and all of its attributes
> > pre-joined -- so each record in the fact table would have a
> year and a
> > quarter -- then this API for non-JDBC fact data would be workable.
> > I don't want to put you off. I'd like to continue this
> discussion, since it
> > would give us the opportunity to use a distributed cache or
> to delegate work
> > to one or many slave servers.
> > Julian
> >> -----Original Message-----
> >> From: mondrian-bounces at pentaho.org
> >> [mailto:mondrian-bounces at pentaho.org] On Behalf Of Torsten
> >> Sent: Friday, August 07, 2009 9:24 AM
> >> To: mondrian at pentaho.org
> >> Subject: [Mondrian] Integrating data from non-JDBC data sources
> >> Dear list!
> >> I am sure this question has been asked several times already,
> >> but I was unable to find any usable answers.
> >> My goal is to make Mondrian access a fact table from a data
> >> source which isn't JDBC. Is there any code available yet for
> >> that? Should this be easy to implement or are there any
> >> design decisions in Mondrian / PDI which would make this a
> >> larger endeavor?
> >> Any pointers to information which I have missed are very welcome.
> >> Regards,
> >> Torsten
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