[Mondrian] Does order of dimension in NECJ matter with regards to performance?

Peter Tran ptran at prospricing.com
Thu Sep 27 11:22:29 EDT 2007


Hi Zelaine,

Do we really delegate all these NECJ to the underlying RDBMS?  Are you
saying that we actually generate a SQL that joins across all those
dimensions?  That's not what I'm seeing when I turn on the trace to view
the actual SQL.

It looks like we do some of this filtering internally in memory within
Mondrian.

Am I wrong?

Thanks,
-Peter

-----Original Message-----
From: mondrian-bounces at pentaho.org [mailto:mondrian-bounces at pentaho.org]
On Behalf Of Zelaine Fong
Sent: Thursday, September 27, 2007 10:17 AM
To: Mondrian developer mailing list
Subject: Re: [Mondrian] Does order of dimension in NECJ matter with
regardsto performance?

It shouldn't, unless the underlying DBMS you're using has limitations in

how it optimizes join queries.

-- Zelaine

Peter Tran wrote:
> Hi,
> 
> If I have multiple dimensions nested within NECJ, does the order of
the
> dimension sets have any impact on performance?
> 
> For example:
> 
> NECJ(NECJ(NECJ(NECJ(dim1, dim2), dim3), dim4), dim5)
> 
> vs.
> 
> NECJ(NECJ(NECJ(NECJ(dim5, dim4), dim3), dim2), dim1)
> 
> Thanks,
> -Peter
> 
> 
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