[Mondrian] Mondrian Performance Issue with Large Dimensions

Tom Barber tom at analytical-labs.com
Tue Oct 18 03:47:56 EDT 2011


Hi Julian,

I got them to check the mondrian property in
system/mondrian/mondrian.properties, and I'm told its already set to true. I
should also point out this when using Analyzer.

Cheers

Tom

On 18 October 2011 08:19, Julian Hyde <jhyde at pentaho.com> wrote:

> Pedro asked me a similar question. See my reply to him (below).
>
> It turns out that option #1 is already implemented. Try setting
> mondrian.olap.elements.NeedDimensionPrefix=true and see whether mondrian
> generates fewer SQL queries. (You'll have to write more explicit MDX of
> course.)
>
> Julian
>
> -------
>
> On Saturday, September 24, 2011, Julian Hyde wrote:
>
> > Ideas to improve "large dimension" performance:
> >
> > 1. Add option that forces strict name resolution. You would not be able
> to write [M], you would have to write [Gender].[M]. Therefore if you wrote
> [Customers] mondrian would not look for a root member called "Customers" in
> every dimension.
> >
> > 2. Specify root members in the schema. E.g.
> >
> > <Attribute name='Gender' ... >
> >  <Members>
> >   <Member key='F'/>
> >   <Member key='M'/>
> >  </Members>
> > </Attribute>
> >
> > 3. Use aggregate tables to find level members. This proposal is flawed,
> because only 'non empty' members would come back. For example, if you asked
> for [Time].[Year].members, 2012 would not be returned from the agg table,
> because we have not yet made a sale in 2012. We would need a way to specify
> that this approximation is safe for a given level.
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